Leicester City opened up a seven-point lead at the Premier League summit by overcoming Southampton 1-0 at the King Power Stadium on Saturday.
Wes Morgan's first-half header was enough for Leicester to secure a fifth single-goal victory in their last six top-flight matches, capitalising on second-placed Tottenham's 1-1 draw at Liverpool on Saturday to extend their advantage at the top.
The afternoon started jovially as, on the eve of his birthday, Leicester chairman Vichai Srivaddhanaprabha laid on free doughnuts and beer for the home faithful.
But after a positive start, Leicester were soon put on the back foot and were fortunate not to concede a penalty when Danny Simpson appeared to block Sadio Mane's shot with his arm inside the box, with referee Michael Oliver unmoved.
Claudio Ranieri's side made the most of the reprieve as Morgan's first Premier League goal of the season ensured they took a lead into half-time.
Southampton goalkeeper Fraser Forster produced a pair of impressive saves to stop Jose Fonte putting through his own goal and keep Simpson at bay after the restart, but one goal proved enough for Leicester to take another step towards a maiden top-flight title.
Ronald Koeman introduced Cedric and Matt Targett in the wing-back positions as he opted for a three-man defence in a bid to boost Southampton's chances of retaining possession, but it was unchanged Leicester who seized the initiative in the early exchanges.
Christian Fuchs headed wide after Shinji Okazaki flicked on a corner from the right, while an important challenge from Fonte stopped the Japanese striker from diverting a cutback from Jamie Vardy.
Unperturbed, Southampton became more adventurous and, after Graziano Pelle steered a header from Cedric's cross over, they came close to taking the lead just after the half-hour mark.
Pelle set Mane through on goal but, having shifted the ball away from Leicester goalkeeper Kasper Schmeichel, his shot was kept out by a last-ditch block from Simpson as legitimate claims he used his arm in the process were ignored by the official.
Schmeichel then kept Fonte's curling strike out of the top corner with a fingertip save, but Leicester responded to the building pressure with the opening goal.
Fuchs was given time and space on the left and he used it to pick out Morgan, who towered over Jordy Clasie to divert his header in off the upright in the 38th minute.
The second half proved a much tighter affair, with chances initially limited until Fonte inadvertently looped Danny Drinkwater's pass from the right wing towards his own goal, needing a superb save from backpedalling Forster to keep it out.
England international Forster produced another brilliant stop when Simpson connected with Vardy's clever ball across the face of goal at the back post, but the defender's shot was placed poorly when he should have given the goalkeeper no chance.
Southampton sent Charlie Austin on for his first appearance in more than month due to a hamstring injury as they searched for an equaliser.
But Leicester came closest to finding the net before the final whistle when Vardy was denied from an acute angle by the legs of Forster as Ranieri's side wound down the clock for a seventh clean sheet in their last eight league home games.
They now need just four victories to be crowned champions, while Southampton remain seventh after suffering a blow to their European hopes.