Match ends, Chelsea 0, West Ham United 0.
Chelsea slipped up in the race for the title as they were held by a dogged West Ham at Stamford Bridge.
The Blues controlled the match but were frustrated by Sam Allardyce's lowly Hammers, who defended stoutly.
Oscar had a shot touched onto the bar by Adrian, who also kept out efforts from John Terry and Samuel Eto'o.
Eto'o thought he had scored late on after assuming the West Ham keeper had wrongly placed the ball for a free-kick, but his effort was disallowed.
That was one of several frantic moments in the last 10 minutes for the visitors, with Frank Lampard forcing Adrian to make a superb save with his feet and another Blues substitute, Demba Ba, hitting the post with a flicked effort.
The result meant the Hammers avoided their 14th defeat in 17 meetings against Chelsea, but they remain in the bottom three.
The hosts, meanwhile, stay two points adrift of Arsenal, who drew with Southampton on Tuesday, but are three behind Manchester City, who went top with a 5-1 win at Tottenham.
Chelsea face City at Etihad Stadium on Monday.
If they are to have any hope of winning that game, Jose Mourinho's attackers must rediscover the killer instinct they were lacking against West Ham, who had conceded 17 goals in their previous five matches.
The visitors showed greater resolve in west London, although it was striker Andy Carroll who was their best defender.
The 25-year-old, making his first league start of the season, was regularly well positioned when Chelsea threatened with set-pieces, but spent more time in his own box than the opposition's.
The hosts dominated possession throughout, but only hit something near top gear towards the end of the first half, when Adrian made excellent saves to keep out Terry's header and Eto'o's fierce drive.
Prior to that, the Spaniard had tipped Oscar's curling effort onto the bar.
Despite their dominance, Chelsea lacked a striker hovering around the six-yard area, with Eto'o often dropping deeper in order to get involved in the build-up.
That pattern continued until the final five minutes, when Ba's close-range flick struck the woodwork.
Lampard also went close to a winner in stoppage time, but his side-footed effort from 10 yards was blocked by the alert Adrian, soon after the goalkeeper had escaped a potentially embarrassing incident.
Eto'o thought he had made a misjudgement when placing the ball for a free-kick and tapped into the net, but referee Neil Swarbrick disallowed the Cameroon striker's effort.
Check out photos from Wednesday's Premier League action at BBC Sport's Facebook page.
- 28AzpilicuetaSubstituted forLampardat 63'minutes
- 12MikelSubstituted forMaticat 63'minutes
- 7Santos do NascimentoBooked at 84mins
- 11OscarSubstituted forBaat 80'minutes
- 17E Hazard
- 4David Luiz
- 17O'BrienBooked at 58mins
- 14TaylorBooked at 61mins
- 21DiaméSubstituted forJarvisat 30'minutes
- 9CarrollSubstituted forColeat 64'minutes
- 4NolanBooked at 74minsSubstituted forNocerinoat 80'minutes
- Neil Swarbrick
- Shots on Target
Second Half ends, Chelsea 0, West Ham United 0.
Attempt missed. Demba Ba (Chelsea) header from the centre of the box is close, but misses to the left. Assisted by Ramires with a cross.
Attempt saved. Frank Lampard (Chelsea) right footed shot from the centre of the box is saved in the centre of the goal. Assisted by Eden Hazard.
Foul by Demba Ba (Chelsea).
Adrián (West Ham United) wins a free kick in the defensive half.
Attempt saved. Eden Hazard (Chelsea) right footed shot from the left side of the box is saved in the centre of the goal.
Attempt missed. Branislav Ivanovic (Chelsea) right footed shot from the centre of the box is close, but misses to the right. Assisted by Demba Ba with a headed pass following a corner.
Corner, Chelsea. Conceded by James Collins.
Attempt missed. Eden Hazard (Chelsea) left footed shot from the left side of the box is just a bit too high. Assisted by Willian.
Demba Ba (Chelsea) hits the left post with a right footed shot from the left side of the six yard box.
Attempt blocked. Frank Lampard (Chelsea) right footed shot from outside the box is blocked. Assisted by Eden Hazard.
Delay over. They are ready to continue.
Joey O'Brien went off injured after West Ham United had used all subs.
Delay in match Joey O'Brien (West Ham United) because of an injury.
Corner, Chelsea. Conceded by Joey O'Brien.
Nemanja Matic (Chelsea) wins a free kick in the defensive half.
Foul by Carlton Cole (West Ham United).
Attempt missed. Branislav Ivanovic (Chelsea) right footed shot from outside the box is close, but misses to the right. Assisted by John Terry.
Attempt blocked. Frank Lampard (Chelsea) right footed shot from the centre of the box is blocked. Assisted by Eden Hazard.