Tottenham ensured Chelsea’s lead at the top of the Premier League remained at nine points after edging past Middlesbrough at White Hart Lane.
Spurs arrived into the clash trailing Antonio Conte’s men by 12 points after the Blues beat north London rivals Arsenal 3-1 in the early kick-off.
But Harry Kane’s second half penalty was enough for Mauricio Pochettino’s men to keep themselves as the most likely challenger to wrestle the title away from Stamford Bridge.
Spurs started the brighter of the two sides and could have taken the lead within five minutes of first half action.
For all of the home side’s possession, set-pieces were becoming a regular feature and it nearly provided a breakthrough close to the half-hour.
Christian Eriksen whipped in a corner and Toby Alderweireld glanced the ball towards goal despite a challenging angle. However, the defender’s attempt ricocheted off the post and out of danger to the relief of Aitor Karanka’s team.
Kane, so often Mauricio Pochettino’s leading man, let himself down with a close range header approaching the interval.
A lovely flowing move involving Ben Davies, Alli and Son eventually saw the ball land on the head of Kane. But the England international failed to get off the floor and saw his effort sail over Valdes’ bar, when the net should have bulged.
But Kane made amends near the hour mark as he put Spurs in front from the penalty spot following good work from Son.
Son manoeuvred his way into the away defence’s box and teased Bernardo with a series of step-overs. The Colombian made the disastrous decision to dive in, leaving Kane with the chance to send Valdes the wrong way and finally give Spurs the lead.
The hosts began to relax, and Son embarked on an ambitious run in an attempt to stretch Spurs’ lead even further.
Alli slipped in Son and targeted his Bernardo once again as he closed in on goal. But the forward’s first touch was heavy, forcing Son to shoot from a tight angle, as the ball fizzed into the side-netting of Valdes’ near post.
Spurs were having it all their own way, but a mix-up between a trio of players prevented the hosts easing any closing stage nerves.
Alli, Kane and Eriksen all attacked in tandem, with the ball eventually falling for Eriksen to take aim. The Dane shaped his body and looked set to bend the ball into the top corner, but Bernardo’s last ditch block saved Middlesbrough.
And the lack of a clinical touch nearly cost Spurs in the dying stages as Marten de Roon wasted a glorious chance to snatch the away side a scarcely deserved point.
Fabio’s long ball forward was helped on by Alvaro Negredo into De Roon’s path, but the midfielder dragged his effort agonisingly wide when he should have left Hugo Lloris stranded.