Roger Federer made a poor start on Sunday when he lost his Round Robin match to Kei Nishikori. In what was an all-UNIQLO sponsored Tennis clash, Federer seemed constantly off as he wasn't able to put things together the way he used to in the past.

Losing in straight sets put Roger Federer in an unpleasant spot as he came to London bearing the hope of gaining the 100th ATP title of his career. With nothing in the bag after the first session, he will collide with Dominic Thiem in today's main event. The Austrian seeks to avenge his first-round defeat too which means both players will be putting up their best efforts.

Whoever loses this encounter will see his chances of qualify for the semis plummeting.

Roger Federer holds an unconvincing and fragile record against Dominic Thiem

Although Dominic Thiem has been around for several years now, he and Roger Federer shared only three matches together. According to atpworldtour.com, all of them occurred back in 2016 and the interesting part is that they were played on three distinct surfaces. While Federer won their first one at the 2016 Brisbane International (hard court), the Austrian took his revenge later that year by defeating Federer both in Rome (outdoor clay) and Stuttgart (grass court). And, this time, the surface will be a different one as well as an indoor hard venue will be the place of battle.

Ranked eighth in the world according to ESPN, the 25-year-old Austrian has qualified for the third consecutive time for the Nitto ATP Finals at the O2 Arena in London. He has never got past the Round Robin stages, and he is off to a poor start this year too.

On the other side, Roger Federer seeks a record-breaking seventh success.

Last year, he was the heavy favorite of the event but he was stunned by David Goffin in the semis.

What dangers loom ahead for Roger Federer?

Making it past the group stages would be a small victory for Federer. Should he qualify from the second place in the designated group, he faces an imminent danger next. As things look at the moment, it's hard to think that Novak Djokovic will somehow loosen the grip on first place in the other group.

In that event, Roger Federer could be facing Novak Djokovic a bit earlier than expected. it would be a real blockbuster semifinal, but it would also strip us out of the opportunity of a magical final at the O2 Arena in London.

Still, Roger Federer must come back to winning ways if he wants to survive the group stages. But the one thing that comes with a certain degree of certainty is that Roger Federer's route to the finals at the ATP Nitto event is paved with tons of questions.