Roger Federer looks on course to capture a seventh ATP Finals title but standing in his way in the semis on Saturday is Belgium’s David Goffin.

The other last-four clash sees tournament debutants Jack Sock and Grigor Dimitrov square off, with both showing some impressive form so far this week.

What is behind Dimitrov’s transformation? And how big of a threat is Sock?

In the video above, Sport360‘s Reem Abulleil and Spanish tennis journalist Marta Mateo sit down to preview the semi-finals at the O2 Arena in London.

Who do you think will make the final?