Grigor Dimitrov vs Dominic Thiem LIVE: Latest ATP World Tour Finals updates

GRIGOR DIMITROV and Dominic Thiem face off in their opening match of the ATP World Tour Finals in Group Pete Sampras.

Dimtirov has never played at the ATP World Tour Finals, having reached his career-high ranking of No 6 earlier this month.

The Bulgarian is in the form of his life having captured three titles in 2017 and also made a run to the semi-final of the Australian Open, where he was beaten by Rafael Nadal, whom he will face later this week.

Thiem meanwhile is hardly a veteran of the tournament - the Austrian made his debut last year in London and lost twice including a remarkable three-setter against Novak Djokovic 7-6, 0-6, 2-6.

With Nadal expected to top the group, these two and David Goffin are likely to be scrapping it out for the second semi-final spot. So who can seize the advantage?

Dimitrov 2-1 Thiem*

So we get to the first changeover as scheduled. Dimitrov has missed just two first serves - by contrast, Thiem has only made three for a 25 per cent success rate.

*Dimitrov 1-1 Thiem

If you're looking for an attractive game of tennis, this might be the one for you. Dimitrov unleashes another brilliant backhand winner off the Thiem first serve before the Austrian shows him a tricky of his own, running round the ball to bend a forehand winner down the line. But Thiem has to go through a number of deuces and save a break point before he can hold.

Dimitrov 1-0 Thiem*

Dimitrov just feeling his way into this match and looks pretty frustrated when he's told he has served a double-fault - only for Hawkeye to show that he hasn't. With some irony, he then double-faults again with no Hawkeye to save him!

A brilliant single-handed backhand winner down the line seals an eventful hold for the Bulgarian.

2pm: Right! That doubles match, which saw Jamie Murray and Bruno Soares beaten by those pesky Bryan brothers, finished almost perfectly on time so Thiem and Dimitrov will be out on court any minute now for their clash.

They have only played each other three times and their meetings on hard courts have been split while their most recent clash came in the last 16 of the Madrid Masters, with Thiem triumphing in a third-set tie-break on the clay.

It all points to a relatively tight match between these two entertaining players.