Nadal’s second loss at the tournament sees him losing chances to progress to the semi-finals.

“To be out of the [Finals], well, that's sport and everything can happen. I didn't arrive to this tournament with the full confidence that you need to win these matches. And in the moments that I had to play well, I didn't play well. I made mistakes. I fought a lot. Both matches I fought. I tried my best all the time, but it wasn't enough to win these matches,” he told the tournament’s official website.

Davydenko, who now has one point, needs a win in his last round-robin group match against Robin Soderling in order to qualify.

“Just winning [one] match, now [I am] 1-1. Still maybe [there is a] chance, maybe not, to come to the semi-final. But after [the] first match, I showed my good tennis in the second match. I was surprising. We'll see if I can show the same tennis in the third match,” the 28-year-old said.

Meanwhile, Soderling has guaranteed himself a semi-final spot, taking the match at the ATP Championships in London. The Swede took the better of 3rd seed Novak Djokovic, 7-6(5), 6-1.

Soderling started with an ace on the first point and let his strong serve carry him throughout the match. He was never broken and finished with 10 aces.

The loss ends Djokovic's 11-match winning streak, but he can still make it into the semis.

Rafael Nadal and Nikolay Davydenko go head-to-head in the night session, both looking to get a win – after losing their opening matches.