Costa one of the world’s best

In reply to that Conte said, “Diego is always in the action for the goal, he’s a fantastic striker and he’s showing it”.

Middlesbrough, joint lowest scorers with 10 goals – the same as Costa – in 12 league games, visit champions Leicester City next knowing they must add firepower to the resolute defensive work which recently earned draws at Arsenal and Manchester City.

“Don’t forget Middlesbrough drew with Arsenal and Man City away. It’s important to kill the game if you have chances because anything can happen from corners and crosses, but I am pleased”.

Chelsea had the first real chance in the 28th minute through Pedro Rodriguez but his close-range effort was tipped over the bar by Victor Valdes.

Aitor Karanka shouldn’t be too disheartened with what he saw of his Middlesbrough side, though.

Conte refused to entertain talk of the Premier League title returning to Stamford Bridge in May, despite a display of ruthless efficiency from his side that again marks them out as serious contenders as the season nears its halfway stage.

“I am really pleased with the attitude of my players”, said Karanka. “I’m seeing with my own eyes that we have special players”.

He said: “I am pleased because in this league, it is very hard to have this success and to win these six games in a row is fantastic”. “It’s important, because to be a complete player you must do both phases, with the ball and without the ball”.

Chelsea almost doubled their lead in the 62nd minute as Costa teed up Pedro, who rattled the crossbar from the edge of the box.

Costa headed down David Luiz’s perfectly flighted diagonal cross and his fellow Spanish worldwide Pedro crashed a shot against the bar. You want even to fight more because you have a coach with that spirit’.

This has allowed Boro stay out of the relegation zone (currently in 15th place); an unlikely result against Chelsea could see them move as high as 12th.

Chelsea, who named an unchanged starting line-up for a club record fifth Premier League game in succession, had plenty of early possession but failed to put any shot on target in the first 25 minutes.

Goalkeeper Thibaut Courtois preserved their latest shut-out late on when he parried a powerful Negredo volley as the hosts belatedly pushed bodies forward.

Chelsea FC grabbed three points at Riverside Stadium in a narrow win Sunday afternoon.