By Steve Tongue
REUTERS - Chelsea manager Antonio Conte found himself earlier this season - his first in charge - being asked most weeks about controlling Spain international Diego Costa's volatile temperament.
Now the forward's scoring and all-round contribution is a more regular topic of conversation after 10 goals and three assists have helped fired them to the top of the Premier League.
"Diego is playing good football, with the ball and without it," Conte said after Sunday's 1-0 away win over a lightweight Middlesbrough. "He's a fantastic striker and is showing this."
The margin was closer than most of 'Boro's vain attempts at avoiding defeat against Chelsea over the past 10 years but, as their manager Aitor Karanka ruefully acknowledged, leaving the livewire Costa free for a second can be fatal.
That was what happened shortly before halftime when four defenders looked like figures in a spot-the-ball competition as the league's top scorer nipped in amongst them and volleyed the decisive goal.
"We knew it was going to be hard but we are in the Premier League and one mistake gets you punished," Karanka told Sky Sports after the home team's seventh straight loss to Chelsea in all competitions without scoring a single goal.
"Diego Costa is one of the top scorers in the world. Before the game I said to my players you can't lose him for one second and they lost him," said Karanka.
Costa was more closely guarded early in the second half but still managed to head down David Luiz's long cross for Pedro to drive the ball against the crossbar.
Had that gone in, Chelsea's manic touchline martinet Conte could have relaxed a little.
Instead, he was concerned that his team might concede their first goal in six league games and throw away two points.
"When you create many chances, it's important to score and then you can arrive at the end without (being) afraid," he said.
"But this is the sixth game in a row we don't concede, which is good news."
With no more international breaks to interrupt their rhythm for several months, both clubs can concentrate fully on their respective ends of the table.
"We have five days after a day off to prepare for a tough game against a strong team like Tottenham," Conte said of Saturday's London derby.
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.
(Editing by Ken Ferris)