Arsene Wenger was left frustrated after Marcos Alonso's clash with Hector Bellerin for Chelsea's first goal left the Arsenal defender unable to recall the scoreline.
Alonso headed home for the Blues 13 minutes into the Stamford Bridge clash after Diego Costa's header had come back off the bar, although Arsenal felt the Spanish defender had fouled Bellerin in the aerial contest.
Bellerin appeared to be caught in the head by Alonso's elbow and needed treatment on the pitch before being substituted, and Wenger was unimpressed with referee Martin Atkinson's decision not to award the Gunners a free kick as they went on to lose 3-1.
"Of course it was a foul but they allowed the goal, " Wenger said.
"I think we started well and then after that it was difficult because we were 1-0 down. We paid for that. we were not good enough in posession.
"We lost many balls in positions where you cannot afford to lose it against a counter-attacking side.
"We did not create enough in the final third. The decison was for me very quick.
"You have to respect it - it was the head.
"Referees are much more severe with tackles on the ground but they let more goals in with elbows to the face - not just today but many other games.
"[Bellerin] didn't know the result of the game at the time."
Asked if Chelsea were likely to win the title now, Wenger said: "They look in full confidence, powerful and strong. It's for them to lose it.
"They are in a very, very strong position. We must focus to win the next game."
Premier League table
| Pos | Team | P | W | D | L | GD | Pts |
| 1 | Chelsea | 24 | 19 | 2 | 3 | 34 | 59 |
| 2 | Tottenham | 23 | 13 | 8 | 2 | 29 | 47 |
| 3 | Arsenal | 24 | 14 | 5 | 5 | 24 | 47 |
| 4 | Liverpool | 23 | 13 | 7 | 3 | 24 | 46 |
| 5 | Man City | 23 | 14 | 4 | 5 | 19 | 46 |
| 6 | Man United | 23 | 11 | 9 | 3 | 12 | 42 |
| 7 | Everton | 23 | 10 | 7 | 6 | 10 | 37 |
| 8 | West Brom | 23 | 9 | 6 | 8 | 2 | 33 |
| 9 | Stoke City | 23 | 7 | 8 | 8 | -6 | 29 |
| 10 | Burnley | 23 | 9 | 2 | 12 | -8 | 29 |
| 11 | West Ham | 23 | 8 | 4 | 11 | -11 | 28 |
| 12 | Southampton | 23 | 7 | 6 | 10 | -5 | 27 |
| 13 | Watford | 23 | 7 | 6 | 10 | -12 | 27 |
| 14 | Bournemouth | 23 | 7 | 5 | 11 | -9 | 26 |
| 15 | Middlesbrough | 23 | 4 | 9 | 10 | -7 | 21 |
| 16 | Leicester City | 23 | 5 | 6 | 12 | -14 | 21 |
| 17 | Swansea City | 23 | 6 | 3 | 14 | -24 | 21 |
| 18 | Crystal Palace | 23 | 5 | 4 | 14 | -9 | 19 |
| 19 | Hull City | 23 | 4 | 5 | 14 | -27 | 17 |
| 20 | Sunderland | 23 | 4 | 4 | 15 | -22 | 16 |
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