José Mourinho had planted a smacker on Steve Clarke's cheek before kick-off, his former No2 welcomed back to these parts with gusto by home support and coaching staff alike even if, by the end of a contest that so nearly delivered a first home league defeat for the Portuguese, the opposing managers appeared united only in vague agreement that the referee Andre Marriner had endured a miserable afternoon.

West Bromwich Albion left outraged at the late penalty which cost them victory, with Chelsea livid it had even come to them chasing the game. Life is rarely dull in this pocket of south-west London.

And so to the furore. The visitors, ahead through Shane Long and Stéphane Sessègnon after Samuel Eto'o's opener, should have wrapped up a first win here in 35 years well before Ramires bustled into the penalty area with seconds remaining of the 94th minute to stagger and fall to the turf as Steven Reid, charging into the box at an angle, held his own line. There was contact, shoulder to shoulder, but the Brazilian appeared to have been on the descent before feeling the right-back at his side.

Marriner blew instantly, then paused, as if for dramatic effect, before pointing to the spot. "When the whistle went I thought he was going to book [Ramires] for diving," said Reid, who had been making his first Premier League start of the campaign. "Ramires has gone to ground really easily. It felt soft, like I had stood my ground. Looking at the replays afterwards, there has been no raising of the arm, my arms are by my side, so for us it is very harsh."

Clarke agreed, citing penalty decisions that had gone against his team in matches with Southampton and Stoke already this term to cost Albion five points. Howard Webb had apologised for a non-award at the Britannia Stadium though, in that context, this latest setback was greeted more with resignation.

Mourinho, who had watched the recalled Eden Hazard guide in the spot-kick to extend that unbeaten home record to 66 fixtures, felt the award was actually one of the few key decisions Marriner had called correctly. His principal gripe was Claudio Yacob's dispossession of Branislav Ivanovic in the build-up to Sessègnon's second even if, on subsequent viewing, any foul was hardly clear-cut.

"I am in no doubt that there is a big mistake from the referee for their second goal," said the Chelsea manager. "So if someone has a reason to be upset [it is us]. I'm sorry to say the referee made loads of mistakes today, and all of them against us. The biggest mistake was clearly their second goal, but I don't change my opinion. Andre is one of the best in England and Europe. I won't change my opinion because he has one bad game."

As it was, both these teams could draw considerable encouragement from their displays. West Bromwich have such presence and power down the spine of their side that any fear this season could prove a struggle already feels misplaced. In Long, a striker almost shipped out to Hull City on transfer deadline day, they had a player revived.

When he performs with this level of feverish industry it seems outlandish that he might have been discarded, though Gareth McAuley, Jonas Olsson and Youssouf Mulumbu were just as impressive. This team continues to develop. "The gap is getting closer between the middle tier and the top-end clubs," said Clarke. "The league is growing, more money is being spent. That can only be good for the competition."

Chelsea must rise to that challenge, and their refusal to wilt was heartening, prompting comparisons with Sir Alex Ferguson's Manchester United, whose constant probing would often draw late rewards from apparent lost causes. "We threw everything at them so, emotionally, yes, we found a way," said Mourinho. "We could have died with that second goal, but the boys fought for life. Everything we did was because of a strong personality. We had a bad result – because drawing at home to West Brom isn't a good result – but we rescued a point."

Man of the match Shane Long (West Bromwich Albion)