Chelsea extended their lead atop the Premier League table to six points, but failed to fully capitalise on Manchester City's beating by Burnley after being held by Southampton for the second time this season.
The Blues, looking to shake off Wednesday's Champions League disappointment against Paris Saint-Germain, enjoyed the perfect start; Branislav Ivanovic crossing for Diego Costa to head home the opener.
But the advantage proved to be short-lived. Nemanja Matic was adjudged to have upended the lively Sadio Mane inside the penalty area, allowing Dusan Tadic to score from the spot, straight down the middle.
Thibaut Courtois had already made one instinctive save to deny Mane before the leveller, and was soon in action again to repel Tadic's half-volley as the visitors continually caused problems in the first half.
Jose Mourinho's men appeared revitalised upon the restart and would go on to dominate the second period. But despite 17 second-half attempts on goal to Saints' 5, the hosts couldn't find the breakthrough.
Cesc Fabregas completed more than 100 passes and created 4 chances, while Morgan Schneiderlin put in a standout display, making a game-high 21 ball recovieres and 9 interceptions as well winning 10 tackles.
- Chelsea conceded only their 6th goal at home in the Premier League this season.
- The Saints have scored 52 of their 55 Premier League penalties – the highest rate of any team (minimum 10 taken).
- Dusan Tadic became the 10th Southampton player to score a Premier League penalty for the Saints.
- Chelsea have dropped points in 3 of their last 4 home games, having won the previous 10 before that.
- In fact, Chelsea have scored just 1 goal in each of their last 4 at home, having scored at least twice in the previous 10.
- Southampton have not conceded more than 1 goal in a Premier League away game since the opening weekend (2 vs Liverpool).
- Ronald Koeman’s side have lost just 1 of their last 6 Premier League away games (W4 D1).
- In the last 4 fixtures between these sides at Stamford Bridge, the team scoring first has failed to win.
- Chelsea have taken 22 points in the league since Christmas, three more than Man City but 8 fewer than Arsenal.
- 17 of Chelsea’s 22 shots came in the second half, 11 of them in the closing 20 minutes of the game.