West Ham United climbed to second in the Championship as Divine Mukasa's first-half goal proved enough to secure an eye-catching victory at leaders Swansea City.

Mukasa's calm finish was the decisive moment of an engaging contest in which both sides wasted big chances.

Swansea captain Ben Cabango came closest to an equaliser when he rattled the woodwork, while goalkeeper Lawrence Vigouroux made a string of second-half saves to keep the home side in the game.

West Ham's victory means they are just a point behind Swansea, who remain top of the table despite losing for only the second time this season.

The Hammers are now unbeaten in nine league games since a shock home loss to Charlton Athletic in mid-August.

This was a sixth victory in their 11 second-tier fixtures since relegation from the Premier League last season, and was perhaps the most notable yet given Swansea's superb form in the early stages of this campaign.

Swansea will feel they created enough to maintain this season's unbeaten home league record, though West Ham might easily have won more comfortably given their menace in the second period.

The game had been tight, tense and without any sign of a chance until Marko Stamenic was dispossessed in his own half 11 minutes before half-time and West Ham capitalised.

Mohamadou Kante burst into the penalty area and squared for Mukasa to guide the ball beyond a helpless Vigouroux from 10 yards.

Mukasa's goal, which came through the first shot of the game at either end, prompted more attacking intent from Swansea.

Ronald unleashed a fierce drive which deflected just off target before Ben Cabango thumped a shot against the bar after Josh Tymon's free-kick was not cleared.

West Ham wasted opportunities to pull clear early in the second half, with Swansea goalkeeper Vigouroux twice saving from Jarrod Bowen and denying Pablo when the striker was through on goal.

Back came Swansea, with Adam Idah hooking off target before another set-piece dropped to Cabango and this time the centre-back dragged wastefully wide midway through the second half.

Though tension remained right up until the final whistle, that proved to be Swansea's last major chance as West Ham maintained their unbeaten record on the road this season.

It is no surprise to see West Ham, who are widely regarded as favourites for the Championship title, flying high as the table begins to take shape.

But few had anticipated before the season started that Swansea might have a say in the automatic promotion race.

A tally of 23 points from the first 10 league fixtures of the season – Swansea's best start in 103 years – has Swans fans dreaming of a return to the Premier League eight years after the Welsh club dropped out of the top flight.

A first home defeat since April checks Swansea's momentum, though they pushed Nuno Espirito Santo's powerful West Ham side close in front of a new record Swansea.com Stadium crowd of 20,973.

For much of the first half it seemed like being a day where defences would shine, but the game opened up after on-loan Manchester City teenager Mukasa found a way past the continually impressive Vigouroux.

With West Ham back where they expect to be, in the division's top two, Swansea must now find a response as they attempt to prove they can stay alongside them.

Swansea head coach Vitor Matos:

"A really tight game, decided in the boxes I would say. West Ham scored. With that they are a really well-organised team defending-wise, hard to break them, hard to push them back.

"We still did that. Had some chances, two from set-pieces, didn't score and that's the story of the game I would say.

"That's what we need to take from the game, that in a tight game, small things can make a difference. Unfortunately for us we didn't score."

West Ham boss Nuno Espirito Santo:

"I think it's a good week that didn't start very well for us.

"A very demanding week in terms of the opponents that we had to face, but it finished really well due to the hard work of the boys.

"The commitment, the unity, the way they played today was really good against a very good Swansea side that had its chances also. It was a very intense football match."