World number one Novak Djokovic began his ATP World Tour Finals campaign with a 7-6 (7-4) 6-3 straight-sets win over Jo-Wilfried Tsonga in London.
It was Djokovic fifth victory of the year over the Frenchman and it took him took him to the top of group a.
The top seed won the Australian open in January and is looking to sign off the season in style after ensuring he will top the year-end rankings for the second season in succession.
In other ATP World Tour tie, us open champion and Olympic gold medalist, Andy Murray battled his way to an edgy 3-6 6-3 6-4 opening win against Tomas Berdych
The opening day of round-robin singles action at the O2 arena went with the seedings and put Djokovic and Murray on track to take the two semi-final places in their groups