EPL: Leaders Chelsea held to a 1-1 draw by Southampton

Chelsea were frustrated by Southampton's dogged defending and Fraser Forster's saves on Sunday, going six points clear of Manchester City with a 1-1 draw but missing the chance to open up a bigger lead at the Premier League summit.

Against an energetic and creative Southampton side, Chelsea seemed to experience a Champions League hangover, four days after being eliminated by Paris Saint-Germain.

Although Diego Costa ended a seven-game goal drought for Chelsea, Southampton quickly leveled from the spot through Dusan Tadic in the 19th minute and seized the initiative.

Goalkeeper Thibaut Courtois came to Chelsea's rescue with instinctive saves in the first half. And Chelsea were then repeatedly thwarted after the break by Forster demonstrating why Southampton have conceded the fewest goals this season.

After opening the league season with 10 successive home wins, Chelsea have drawn three of their last four at Stamford Bridge.

But it would take an epic collapse for Chelsea to miss out on their first Premier League title since 2011. Not only does Jose Mourinho's team now have a six-point cushion at the top, but they have a game in hand over second-place defending champion City. And the PSG loss leaves Chelsea with only the league to play for, having already collected the League Cup.

When Chelsea's Champions League campaign ended, the inquest highlighted Costa's failure to score once in Europe this season for Chelsea.

So prolific in front of goal in the first half of the domestic season, Costa's finishing has evaded him. But the Spain striker just took 11 minutes to start and complete the move for the opener in a vibrant opening for the hosts.

Eden Hazard, released by Costa, held off Jose Fonte before sending the ball out wide to Branislav Ivanovic, who provided a pinpoint cross for Costa's header.

The lead was immediately protected by Courtois pushing away Sadio Mane's shot. But Mane was tripped by Nemanja Matic shortly afterward in the penalty area. Tadic sent the ball down the middle, going into the net after clipping Courtois' feet.

Chelsea's own penalty appeal was dismissed by referee Mike Dean when Ivanovic went down after being clipped by Tadic.

Southampton's bursts forward were unsettling the hosts, with Mane particularly menacing and Tadic lively.

Courtois preserved parity before halftime by denying Tadic and diving low to block Mane's strike. And at the start of the second half, the Belgium goalkeeper palmed away one-handed a free kick from Toby Alderweireld, and Mane's follow-up overhead kick was also blocked.

Costa was looking determined to make up for his recent barren spell in front of goal, appealing for a penalty after being fouled by Fonte and then trying his luck with an overhead kick from Hazard's cutback.

Southampton's rearguard was superb, with Chelsea finding no way through.

Midway through the half, Forster pulled off a double save - scooping away Oscar's header and batting clear a follow-up from Cesc Fabregas, who has faded in the second half of his first season at Chelsea.

The saves continued after the clock hit 90 minutes, with Cesar Azpilicueta's effort repelled by Forster and substitute Loic Remy denied. The point keeps Southampton in touch with an unexpected challenge for the top four Champions League places.