Ivan Toney struck as Brentford denied Arsenal victory, giving Manchester City the chance to close the gap at the top of the table to three points on Sunday.
A first goal for January signing Leandro Trossard put Arsenal ahead on 66 minutes in a match where Brentford had the better chances.
A deserved equaliser came eight minutes later when Arsenal failed to clear a free-kick and Toney nodded in.
After dropping points for the second match running, Arsenal are six points clear of Man City, who host Aston Villa tomorrow.
City know a win over Villa would allow them to leapfrog the leaders when the two teams face each other on Wednesday.
Newcastle United missed a chance to go third overnight and close the gap to Arsenal to eight points after they were held to a 1-1 draw by AFC Bournemouth.
Marcos Senesi put AFC Bournemouth ahead on the half-hour but Miguel Almiron ended a five-match scoreless run for his 10th league goal of the season to level for Newcastle just before half-time.
Eddie Howe, on his return to Vitality Stadium, would have been frustrated that his side were unable to get another goal and their league-leading 11th draw leaves them fourth on 41 points, two behind Manchester United.
A second point in seven matches keeps AFC Bournemouth in 19th on 18 points.
Leicester City earned back-to-back comeback wins, scoring four goals, winning 4-1 at home to Tottenham Hotspur, who missed the chance to go fourth with a victory.
Rodrigo Bentancur had put Spurs ahead early on, before going off injured. But two goals inside three minutes from Nampalys Mendy and James Maddison turned the match around.
Kelechi Iheanacho doubled the lead in first-half stoppage time and Harvey Barnes got the fourth after combining with Maddison.
Fulham are up to seventh after a 2-0 win over in-form Nottingham Forest. Willian put Fulham ahead with a wonderful curling strike.
Substitute Manor Solomon's first league goal for Fulham sealed the only win for a team in the top half of the table on Saturday.
Fulham now have 35 points, while a first defeat in six matches for Forest drops them to 14th with 24 points, six clear of the bottom three.
For the fourth year in a row Crystal Palace and Brighton & Hove Albion shared the points in the "M23 derby" at Selhurst Park.
Solly March's neat finish put Brighton ahead in the second half but James Tomkins profited from a goalkeeping howler by Robert Sanchez six minutes later to make it honours even.
Palace stay 12th on 25 points, while Brighton are sixth with 10 points more.
A late goal from substitute Joao Gomes on his debut handed 10-man Wolverhampton Wanderers a crucial 2-1 win over relegation rivals Southampton and put pressure on Saints manager Nathan Jones.
Southampton seemed in control after January signing Carlos Alcaraz scored his first goal for the club and Wolves midfielder Mario Lemina was sent off midway through the first half against his former side.
But Jan Bednarek bundled the ball into the back of his own net to make it 1-1, before Joao Gomes came on for the winner three minutes from time to take Wolves' points total to 23, five clear of the relegation zone, in 15th.
A seventh defeat in eight matches for Jones leaves Southampton bottom on 15 points.
Chelsea showed promising sparks in their attack but were held by a dogged West Ham United in a 1-1 draw at the London Stadium.
Chelsea took the lead through Joao Felix's first goal for the club, a brilliant first-time volley from Enzo Fernandez's cross. It was also their first goal in three matches.
West Ham levelled against the run of play. Emerson scored at the back post against his former club, the first goal Graham Potter's team had conceded in four matches.
A third consecutive draw for Chelsea keeps them in ninth, with 31 points, 10 from the top four. West Ham move up one place to 16th with 20 points.
Ahead of Man City's match with Villa, Leeds United and Man Utd face each other for the second time in under five days.
Man Utd will be looking to extend their lead over Newcastle to five points and close the gap to Arsenal also to five points.
Leeds and caretaker boss Michael Skubala are looking for a first win in nine matches to go back to 16th.