Chelsea reclaimed the Premier League summit for the first time since August after Diego Costa's sole goal gave manager Antonio Conte's side a 1-0 win over Middlesbrough and extended his lead as the division's top scorer.
Costa became the first Premier League player to hit double-digit scoring figures this season after netting his 10th of the campaign at the Riverside Stadium, where the Blues also moved one point clear of the competition.
Following Liverpool's 0-0 stalemate at Southampton on Saturday, Chelsea capitalised by exacting their vengeance on less seasoned top-flight opposition, as well as securing their sixth successive clean sheet in the process.