'It was a great cross!': David Moyes accepts luck was on his side in derby win

Arthur Masuaka scored a sensational winning goal as West Ham came back from behind twice to beat league-leaders Chelsea

West Ham United's Arthur Masuaku (no.26) celebrates scoring their side's winner against Chelsea

Arthur Masuaku scored a sensational winning goal as West Ham came back from behind twice to beat league-leaders Chelsea in an enthralling London derby.

West Ham's left-back went on halfway through this gripping encounter as substitute for the injured Ben Johnson, and he settled the game with a swerving shot from way out on the left touchline that Edouard Mendy got a hand to but could not stop.

While debate was raging on social media whether Masuaku meant it as a shot or a cross, his manager admitted the Congolese international got lucky.

“It was a great cross!” said David Moyes with a smile. “You have to get the ball in the box and we've all seen other types of goals from crosses where it has dipped over the goalkeeper, in at the back post and different things.

“So look, I think we have to say it is a bit of a lucky goal, but in midweek we didn't get a goal to make it 2-0 when VAR went against us which for the life of me I cannot see how that was ruled out. “You have to take what you get in football, and today we got that goal to win 3-2.”

It capped a remarkable comeback from the Hammers, who showed their credentials for a Champions League spot with another significant scalp, having already beaten Tottenham, Liverpool and Manchester United and Manchester City in league and cup competitions this season.

It was a major setback for Chelsea's title ambitions too, as they were knocked off the top of the table when Liverpool beat Wolves a few hours later.

The Blues have only conceded two or more goals in a match three times since Thomas Tuchel arrived last January, and have now lost on all three occasions.

They went ahead with a Thiago Silva header in the 28th minute, before Manuel Lanzini equalised from the penalty spot after Mendy tripped Jarrod Bowen following a terrible back-pass from Jorginho.

Mason Mount restored Chelsea's lead with a superb goal shortly before half-time, volleying Hakim Ziyech's deep cross past Lukasz Fabianski with perfect technique.

But West Ham were not to be beaten. Bowen, the game's outstanding player, equalised in the 56th minute with a long shot through the legs of Andreas Christensen, and with the full time whistle approaching, Masuaku sent his speculative shot flying in from the left. Whether he intended it as a shot or cross remains to be seen, but it certainly settled this game and led to wild celebrations from home supporters, some of whom had booed their team off the pitch following their draw with Brighton last weekend.

Tuchel refused to blame Edouard Mendy for his errors but said: “Edou is dealing with a rough period. I don't know why exactly but he seems to have lost a bit of confidence. His decision making was not on the highest level today for the first goal, but also we put him in a really awkward situation.

“We are far, far away from blaming anybody but we need to admit that we are making too many crucial mistakes at the moment, which cost us a win against Manchester United (last weekend) and today as well.

“I thought the performance today was enough to win the game but we give easy goals away and this is very unusual. We make big mistakes that lead to big chances that lead to easy goals.

“We have done this now in three matches, against United, Watford and again today. If you do this at this kind of level, you can't expect to have a result."

The Chelsea coach also has more injuries too, with both Kai Havertz and Marcos Alonso joining a long injured list, as well as Jorginho having to play with a hip problem.

“Kai has huge pain, Marcos Alonso has back pain, so that is another two substitutes we had to make because of to injury. Jorgi has been playing with hip pain for many matchdays and you can see it. We are missing not only N'Golo (Kante), but also Mateo Kovacic for five or six weeks. I don't know when N'Golo will be back.”

Tuchel blamed the fixture list, with Chelsea currently playing two matches each week.

“We have some overloaded players. This is not an excuse but if you look at our schedule, there is no escape and this is exactly where we struggle at the moment.

“We have crucial ball losses in situations where you simply cannot have them if you want clean sheets and want to dominate games. If you want to protect against counter attacks, it is impossible to do these kinds of mistakes, three times in a row, it is simply too much and we cannot give any excuses that we are tired.

“It is absolutely normal to be tired through the Premier League in winter. It is a question of precision, details, risk management, where you take it and where you absolutely don't.

If you invite a team like West Ham into your own box, into the last 20 metres by giving big ball losses then you are in the trouble.”