diff --git a/spring-session-data-redis/src/integration-test/java/org/springframework/session/data/redis/ReactiveRedisOperationsSessionRepositoryITests.java b/spring-session-data-redis/src/integration-test/java/org/springframework/session/data/redis/ReactiveRedisOperationsSessionRepositoryITests.java
index 69861eb8..816cef94 100644
--- a/spring-session-data-redis/src/integration-test/java/org/springframework/session/data/redis/ReactiveRedisOperationsSessionRepositoryITests.java
+++ b/spring-session-data-redis/src/integration-test/java/org/springframework/session/data/redis/ReactiveRedisOperationsSessionRepositoryITests.java
@@ -16,6 +16,8 @@
 
 package org.springframework.session.data.redis;
 
+import java.time.Instant;
+
 import org.junit.Test;
 import org.junit.runner.RunWith;
 
@@ -191,6 +193,28 @@ public class ReactiveRedisOperationsSessionRepositoryITests extends AbstractRedi
 		assertThat(this.repository.findById(originalId).block()).isNull();
 	}
 
+	// gh-1111
+	@Test
+	public void changeSessionSaveOldSessionInstance() {
+		ReactiveRedisOperationsSessionRepository.RedisSession toSave = this.repository
+				.createSession().block();
+		String sessionId = toSave.getId();
+
+		this.repository.save(toSave).block();
+
+		ReactiveRedisOperationsSessionRepository.RedisSession session = this.repository
+				.findById(sessionId).block();
+		session.changeSessionId();
+		session.setLastAccessedTime(Instant.now());
+		this.repository.save(session).block();
+
+		toSave.setLastAccessedTime(Instant.now());
+		this.repository.save(toSave).block();
+
+		assertThat(this.repository.findById(sessionId).block()).isNull();
+		assertThat(this.repository.findById(session.getId()).block()).isNotNull();
+	}
+
 	@Configuration
 	@EnableRedisWebSession
 	static class Config extends BaseConfig {
diff --git a/spring-session-data-redis/src/main/java/org/springframework/session/data/redis/ReactiveRedisOperationsSessionRepository.java b/spring-session-data-redis/src/main/java/org/springframework/session/data/redis/ReactiveRedisOperationsSessionRepository.java
index 2b922563..379ed29d 100644
--- a/spring-session-data-redis/src/main/java/org/springframework/session/data/redis/ReactiveRedisOperationsSessionRepository.java
+++ b/spring-session-data-redis/src/main/java/org/springframework/session/data/redis/ReactiveRedisOperationsSessionRepository.java
@@ -143,24 +143,39 @@ public class ReactiveRedisOperationsSessionRepository implements
 
 	@Override
 	public Mono<Void> save(RedisSession session) {
-		return session.saveDelta().and((s) -> {
-			if (session.isNew) {
-				session.setNew(false);
-			}
-
-			s.onComplete();
-		});
+		Mono<Void> result = session.saveChangeSessionId().and(session.saveDelta())
+				.and((s) -> {
+					session.isNew = false;
+					s.onComplete();
+				});
+		if (session.isNew) {
+			return result;
+		}
+		else if (session.hasChangedSessionId()) {
+			String sessionKey = getSessionKey(session.originalSessionId);
+			return this.sessionRedisOperations.hasKey(sessionKey)
+					.flatMap((exists) -> exists ? result : Mono.empty());
+		}
+		else {
+			String sessionKey = getSessionKey(session.getId());
+			return this.sessionRedisOperations.hasKey(sessionKey)
+					.flatMap((exists) -> exists ? result : Mono.empty());
+		}
 	}
 
 	@Override
 	public Mono<RedisSession> findById(String id) {
 		String sessionKey = getSessionKey(id);
 
+		// @formatter:off
 		return this.sessionRedisOperations.opsForHash().entries(sessionKey)
 				.collectMap((e) -> e.getKey().toString(), Map.Entry::getValue)
-				.filter((map) -> !map.isEmpty()).map(new SessionMapper(id))
-				.filter((session) -> !session.isExpired()).map(RedisSession::new)
+				.filter((map) -> !map.isEmpty())
+				.map(new SessionMapper(id))
+				.filter((session) -> !session.isExpired())
+				.map(RedisSession::new)
 				.switchIfEmpty(Mono.defer(() -> deleteById(id).then(Mono.empty())));
+		// @formatter:on
 	}
 
 	@Override
@@ -285,12 +300,8 @@ public class ReactiveRedisOperationsSessionRepository implements
 			return this.cached.isExpired();
 		}
 
-		public void setNew(boolean isNew) {
-			this.isNew = isNew;
-		}
-
-		public boolean isNew() {
-			return this.isNew;
+		private boolean hasChangedSessionId() {
+			return !getId().equals(this.originalSessionId);
 		}
 
 		private void flushImmediateIfNecessary() {
@@ -305,38 +316,35 @@ public class ReactiveRedisOperationsSessionRepository implements
 		}
 
 		private Mono<Void> saveDelta() {
-			String sessionId = getId();
-			Mono<Void> changeSessionId = saveChangeSessionId(sessionId);
-
 			if (this.delta.isEmpty()) {
-				return changeSessionId.and(Mono.empty());
+				return Mono.empty();
 			}
 
-			String sessionKey = getSessionKey(sessionId);
-
+			String sessionKey = getSessionKey(getId());
 			Mono<Boolean> update = ReactiveRedisOperationsSessionRepository.this.sessionRedisOperations
 					.opsForHash().putAll(sessionKey, this.delta);
-
 			Mono<Boolean> setTtl = ReactiveRedisOperationsSessionRepository.this.sessionRedisOperations
 					.expire(sessionKey, getMaxInactiveInterval());
 
-			return changeSessionId.and(update).and(setTtl).and((s) -> {
+			return update.and(setTtl).and((s) -> {
 				this.delta.clear();
 				s.onComplete();
 			}).then();
 		}
 
-		private Mono<Void> saveChangeSessionId(String sessionId) {
-			if (sessionId.equals(this.originalSessionId)) {
+		private Mono<Void> saveChangeSessionId() {
+			if (!hasChangedSessionId()) {
 				return Mono.empty();
 			}
 
+			String sessionId = getId();
+
 			Publisher<Void> replaceSessionId = (s) -> {
 				this.originalSessionId = sessionId;
 				s.onComplete();
 			};
 
-			if (isNew()) {
+			if (this.isNew) {
 				return Mono.from(replaceSessionId);
 			}
 			else {
diff --git a/spring-session-data-redis/src/test/java/org/springframework/session/data/redis/ReactiveRedisOperationsSessionRepositoryTests.java b/spring-session-data-redis/src/test/java/org/springframework/session/data/redis/ReactiveRedisOperationsSessionRepositoryTests.java
index a4b52a1b..0530e435 100644
--- a/spring-session-data-redis/src/test/java/org/springframework/session/data/redis/ReactiveRedisOperationsSessionRepositoryTests.java
+++ b/spring-session-data-redis/src/test/java/org/springframework/session/data/redis/ReactiveRedisOperationsSessionRepositoryTests.java
@@ -183,6 +183,7 @@ public class ReactiveRedisOperationsSessionRepositoryTests {
 
 	@Test
 	public void saveSessionNothingChanged() {
+		given(this.redisOperations.hasKey(anyString())).willReturn(Mono.just(true));
 		given(this.redisOperations.expire(anyString(), any()))
 				.willReturn(Mono.just(true));
 
@@ -191,12 +192,14 @@ public class ReactiveRedisOperationsSessionRepositoryTests {
 
 		StepVerifier.create(this.repository.save(session)).verifyComplete();
 
+		verify(this.redisOperations).hasKey(anyString());
 		verifyZeroInteractions(this.redisOperations);
 		verifyZeroInteractions(this.hashOperations);
 	}
 
 	@Test
 	public void saveLastAccessChanged() {
+		given(this.redisOperations.hasKey(anyString())).willReturn(Mono.just(true));
 		given(this.redisOperations.opsForHash()).willReturn(this.hashOperations);
 		given(this.hashOperations.putAll(anyString(), any())).willReturn(Mono.just(true));
 		given(this.redisOperations.expire(anyString(), any()))
@@ -206,6 +209,7 @@ public class ReactiveRedisOperationsSessionRepositoryTests {
 		session.setLastAccessedTime(Instant.ofEpochMilli(12345678L));
 		Mono.just(session).subscribe(this.repository::save);
 
+		verify(this.redisOperations).hasKey(anyString());
 		verify(this.redisOperations).opsForHash();
 		verify(this.hashOperations).putAll(anyString(), this.delta.capture());
 		verify(this.redisOperations).expire(anyString(), any());
@@ -219,6 +223,7 @@ public class ReactiveRedisOperationsSessionRepositoryTests {
 
 	@Test
 	public void saveSetAttribute() {
+		given(this.redisOperations.hasKey(anyString())).willReturn(Mono.just(true));
 		given(this.redisOperations.opsForHash()).willReturn(this.hashOperations);
 		given(this.hashOperations.putAll(anyString(), any())).willReturn(Mono.just(true));
 		given(this.redisOperations.expire(anyString(), any()))
@@ -229,6 +234,7 @@ public class ReactiveRedisOperationsSessionRepositoryTests {
 		session.setAttribute(attrName, "attrValue");
 		Mono.just(session).subscribe(this.repository::save);
 
+		verify(this.redisOperations).hasKey(anyString());
 		verify(this.redisOperations).opsForHash();
 		verify(this.hashOperations).putAll(anyString(), this.delta.capture());
 		verify(this.redisOperations).expire(anyString(), any());
@@ -242,6 +248,7 @@ public class ReactiveRedisOperationsSessionRepositoryTests {
 
 	@Test
 	public void saveRemoveAttribute() {
+		given(this.redisOperations.hasKey(anyString())).willReturn(Mono.just(true));
 		given(this.redisOperations.opsForHash()).willReturn(this.hashOperations);
 		given(this.hashOperations.putAll(anyString(), any())).willReturn(Mono.just(true));
 		given(this.redisOperations.expire(anyString(), any()))
@@ -252,6 +259,7 @@ public class ReactiveRedisOperationsSessionRepositoryTests {
 		session.removeAttribute(attrName);
 		Mono.just(session).subscribe(this.repository::save);
 
+		verify(this.redisOperations).hasKey(anyString());
 		verify(this.redisOperations).opsForHash();
 		verify(this.hashOperations).putAll(anyString(), this.delta.capture());
 		verify(this.redisOperations).expire(anyString(), any());