London - Andy Murray needed a three-hour struggle to tighten the race for a spot in the weekend semi-finals of the ATP World Tour Finals, with the Scot narrowly beating Spain's Fernando Verdasco 6-4, 6-7 (4-7), 7-6 (7-3) Thursday. With the round-robin group tightly knit, it will all come down to a later match-up between top seed Roger Federer and Argentine Juan Del Potro to determine which two of the four men reach Saturday's semi-finals of the year-end championships.
According to ATP calculations, Federer could simplify the situation with a win, which would send himself and Murray into weekend play.
A Del Potro win in two sets would put Federer and the Argentine through - eliminating Murray - while a three-set del Potro result would trigger a nightmare scenario.
With Federer, Murray and Del Potro then equal on wins and sets, the resulting tie would have to be broken by games won.
As a result, almost all options remain on the statistical table for the Group A quartet.
The situation is slightly clearer in rival Group B after Robin Soderling clinched the first of the semi spots on Wednesday and Rafael Nadal was definitely eliminated from further contention.
Group play wraps up on Friday as number two Nadal plays Soderling's most recent victim, Novak Djokovic, and Nikolay Davydenko, conqueror of Nadal, plays Soderling.
Murray had to scramble until the end to subdue Verdasco, a victory which produced 18 aces for the Scot.
But Murray's conversion percentage on the day was poor, with the home hero managing on just one of 13 break point chances.
Murray struck 39 winners and 28 unforced errors, finally. getting a grip on the high-voltage marathon as a Verdasco double-fault sent the Spaniard to a 2-4 tiebreak deficit in the final set tiebreaker.
Murray soon managed three match points, converting on the first as a Verdasco volley at the net touched just wide.
