Arsenal 0 Chelsea 0: Oscar decision in the spotlight after stalemate
Leaders Chelsea and title rivals Arsenal played out a feisty goalless Premier League draw at the Emirates Stadium with much of the discussion centring on four penalty shouts all turned down.
The most prominent involved David Ospina's clumsy first-half collision with Oscar in a keenly-contested stalemate that saw Cesc Fabregas booed on his return to his former club and Jose Mourinho maintain his unbeaten record against Arsene Wenger.
With Diego Costa and Loic Remy injured, Oscar began as the figurehead of Chelsea's attack and was central to the game's biggest talking point as he nodded a header past the onrushing David Ospina.
However, the Brazilian was pole-axed by the Arsenal goalkeeper and, after the effort was cleared away by Hector Bellerin, Chelsea's frustrations were clear as referee Michael Oliver opted against awarding a spot-kick and brandishing a possible red card.
Fabregas then irked the home fans on his first Emirates appearance since leaving for Barcelona in 2011 when he was booked for a perceived dive in the area as a traditionally fiery contest began to heat up.
The London derby struggled to reach the boil after the break, however, despite plenty of attacking intent on show, as Arsenal moved level on points with second-placed Manchester City.
Chelsea, who extended their unbeaten run against Sunday's hosts to eight matches, can no longer win the title at Leicester City on Wednesday, but remain well on course - 10 points clear with a game in hand.
Arsenal edged the initial stages, although Chelsea felt they should have earned an early penalty seven minutes in when Oscar went down under pressure from Bellerin.
Contact was minimal and Oliver waved away protests before Arsenal continued to threaten - Olivier Giroud juggling the ball in the area before Gary Cahill dealt with the danger.
Bellerin was then required to clear Oscar's goal-bound effort following a sublime ball from Fabregas, with Ospina's foul on the forward failing to merit sanctions.
Mourinho was left distinctly unimpressed at the lack of a penalty or a card for the Colombian, although Oscar was able to continue after medical assistance.
Oliver was again at the centre of things 23 minutes in, as was Fabregas, who was adjudged to have dived in the box following a challenge from Santi Cazorla.
It was then Arsenal's turn to unsuccessfully appeal for a spot-kick when Cahill handled after the half-hour mark, Ramires forced Ospina into a smart save following a quick break and clever pass by Willian.
Mourinho replaced Oscar with Didier Drogba at the break and the Chelsea boss saw his side play their part in an open start to the second period.
Both sides countered quickly but struggled to find the final pass - Per Mertesacker miscuing a shot wide before substitute Danny Welbeck failed to sort his feet and fashion an effort following Nacho Monreal's cutback.
Ultimately, Wenger failed to get the better of his opposite number at the 13th attempt, while Mourinho must wait until next Sunday's visit of Crystal Palace for an opportunity to secure Chelsea's fourth Premier League crown providing they win at Leicester.