ATP World Tour Finals

Kerber issues Australian Open warning with Sydney triumph

Dimitrov comes of age to win ATP Finals title

Federer outlasts Del Potro for eighth Basel title

Del Potro overcomes Dimitrov to retain Stockholm title

Djokovic ends Murray's 28-win streak in Qatar triumph

Djokovic thrashes Goffin, picks row with umpire

Djokovic digs deep to repel Raonic onslaught

Returning hero Murray masters Cilic, Nishikori wins

Murray handed tough draw in bid to end year number one