After an uncharacteristically feeble start by to its Premier League title defense, the return of ’s fiery temperament was just what needed to rouse his under-performers against .

2 Sent Off For Arsenal, Costa Escapes Action As Chelsea Wins
Chelsea’s , right heads the Ball to score the opening goal during the English Premier League soccer match between Chelsea and Arsenal at stadium in London. (Image: AP)

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Job done. Even if Costa will do little to endear Chelsea to the neutrals.

There was no goal from last season’s top scorer in Saturday’s 2-0 victory over Arsenal but the hot-headed striker’s contribution seemed even more significant. Costa managed to escape being dismissed for lashing out at Laurent Koscielny before appearing to incite Gabriel Paulista into being sent off for a retaliatory kick on him right in front of the referee

“He can do what he wants and stays on,” Arsenal manager said. “I think it is unacceptable behavior … he will do the same next week and the week after and he always gets away with it. It’s always provocation.”

Arsenal was a man down just before half time and Chelsea made a flying start to the second half. Kurt Zouma headed in the opener after dislodging captain John Terrry — a mainstay in Mourinho’s side — from the starting lineup.

A reckless, but not malicious, sliding tackle on by Santi Cazorla earned the Arsenal midfielder a second yellow card in the 79th minute.

“It was very accidental,” Wenger said.

Arsenal had to cope with nine men and completed Chelsea’s derby triumph in stoppage time with a deflected strike.

This was the day everything went Mourinho’s way against Wenger, his arch adversary, following a spluttering start to the league campaign that had seen Chelsea lose three out of the five games before Saturday.

Not only did Hazard claim his first goal of a season, having struggled to match the player-of-the-year exploits of 2014-15 until now, but Fabregas claimed his first assist after setting up more goals than anyone else in the league last year.

More significantly for Mourinho, it maintained his unbeaten record against Wenger in competitive games after last month losing the Community Shield, which serves as the curtain-raiser to the season.