Costa sent for scans after picking up injury

However, Everton thought they had clinched the points when Ramiro Funes Mori’s diving header gave them the lead again in the 90th minute, but Terry’s back-heel in the 98th minute clinched a point for the home side at Stamford Bridge.

Martínez was aggrieved that Terry’s equaliser had been plundered after 97 minutes 53 seconds when the fourth official’s board had suggested there would be seven minutes of added time, though his real frustration centred on the offside.

Hiddink admitted that Martinez was right to complain: “Sometimes it goes in your favour during a season but you have to be fair”.

Chelsea captain John Terry netted a 98th-minute equaliser almost a full minute after the allotted stoppage time had elapsed and from an offside position. Branislav Ivanovic and Oscar also played their part and despite being offside, his flicked effort stood and the point was sealed.

They appeared to be coasting to a first win in four league outings when Mirallas doubled the lead with a crisp shot after Leighton Baines’ cross. Chelsea had shown little in way of attacking adventure at that point and it was hard to see them mustering two goals and this only made the fightback even more special.

“John Terry with the final touch is two yards offside”.

All the menace was coming from Roberto Martinez’s side and it was rewarded with a second goal in the 56th minute, capping a flowing advance through the brittle home resistance.

The recovery, however, was ultimately out of their reach in what was an afternoon to forget for West Ham but one to leave Newcastle optimistic as the season hots up. “But then the offside decision was as clear as you are going to see as well – it’s a major error”. It’s an important one as we’re still undefeated since the manager [Guus Hiddink] has come in.

It would be a huge blow if Chelsea were to lose Costa as they face a crucial trip to London rivals Arsenal next weekend and Hiddink has few options to choose from up front.

Manchester City returned to the top of the English Premier League table with a 4-0 humbling of high-flying Crystal Palace at the Etihad, thanks to goals from Sergio Aguero (twice), David Silva and Fabian Delph. “Of course I’m not happy with the goals conceded but very happy with the attitude”.

Oviedo took to Twitter to reassure his fans, tweeting: “Great game today, it hurts not have gotten the win”.

Up until the 63rd minute, that is, when Chelsea launched a devastating two goals in two minutes comeback that had owner Roman Abramovich on his feet leading the applause that greeted it.

But Mahrez’s tame attempt from 12 yards was kept out by Mark Bunn, and Villa went on to equalise with 15 minutes remaining via substitute Rudy Gestede’s deflected strike.