LONDON (REUTERS) - Arsenal and Manchester City showed they have the stomach for a title fight on Saturday with the Premier League leaders sinking Newcastle United 1-0 and Manuel Pellegrini's men launching a late comeback to beat Watford 2-1.

There was celebration at last for Manchester United manager Louis van Gaal as his team ended a dismal six-game league streak without a win by defeating Swansea City 2-1.

Arsenal's victory was scrappy and nervy but Laurent Koscielny's 72nd-minute winner was enough to move them two points clear at the summit after Leicester City's surprise push faltered with a goalless draw at home to 10-man Bournemouth.

Manchester City underlined their credentials as Arsenal's main challengers and although they looked forlorn for much of the game at Vicarage Road, they showed their mettle in the closing stages.

Trailing 1-0 to Aleksandar Kolarov's own goal, Yaya Toure volleyed home superbly in the 82nd minute and Sergio Aguero headed the winner moments later to wrap up a precious win that kept them three points behind the pacesetters.

Arsenal are continuing to defy predictions that they lack the consistency of genuine title challengers and while they were not on top form at home to Newcastle, the Londoners did enough to scrape a victory under pressure.

"It was hard work but we prepared ourselves mentally. We were not at our best but we had to dig deep and we can do that when needed," said manager Arsene Wenger as his side chalked up 42 points from 20 games.

Koscielny volleyed home from a corner to help Arsenal forget their Boxing Day blip, when they slumped 4-0 at Southampton, as they notched a second straight victory and a fifth in six games.

That sort of reliability has deserted Leicester over the festive period.

Predictions that their unlikely surge to the top would be short-lived gained further substance when Claudio Ranieri's team failed to score for the third successive game against a Bournemouth side who had Simon Francis sent off after 57 minutes.

Even Riyad Mahrez, their most consistent performer alongside Jamie Vardy, fluffed his lines, failing to convert a penalty after Francis' dismissal.

Manchester City were far more ruthless despite a lacklustre start at Watford.

Toure's volley was expertly angled into the top of the net from a Kolarov corner and Aguero leapt athletically to head in a Bacary Sagna cross two minutes later.

KLOPP FUMES

Wayne Rooney secured the points for Manchester United against Swansea with his first league goal since October, a superb flick in the 77th minute that moved his team up to fifth.

Rooney also climbed above Andy Cole as the second highest scorer in Premier League history with 188 goals.

United had taken the lead with an Anthony Martial header but Gylfi Sigurdsson's glancing effort for Swansea sent nerves jangling at Old Trafford.

Liverpool boss Juergen Klopp was fuming after a 2-0 defeat at West Ham United.

His side's erratic form continued with Andy Carroll delivering the final blow to his former club with a trademark bullet header after Michail Antonio had put West Ham ahead early on.

If Klopp was planning to keep his powder dry in the January transfer window, he may be thinking again after witnessing an insipid attacking display that provoked a fiery response from the German.

"It's not a day for being disappointed, it's a day for being angry," he said. "You cannot win a football match with 90 per cent, you have to do everything ... I don't like it."

Jermain Defoe scored twice for Sunderland whose hopes of avoiding relegation were boosted with a 3-1 win over bottom club Aston Villa.

Alex Tettey scored the only goal of the game for Norwich City against Southampton who had Victor Wanyama sent off in the second half, while Jonny Evans snatched a stoppage-time winner for West Bromwich Albion as they beat Stoke City 2-1.