David Nalbandian advanced to the semi-finals of the Copa Telmex after his opponent Juan Carlos Ferrero retired.
The defending champion and world number 10 was leading 6-3 3-0 and was well on his way to a straight-sets victory before his opponent decided he could no longer continue.
Nalbandian had his serve broken just one time in the 57-minute match.
The Argentinian will face world number 67 Juan Monaco, who needed just 76 minutes to dispatch of Maximo Gonzalez 6-2 6-3. Monaco won this event in 2007.
Joining Nalbandian and Monaco in the semi-finals is third-seeded Tommy Robredo, who extended his winning streak to eight matches with a 6-4 7-6 (7/4) triumph over Franco Ferreiro.
Robredo will face fifth-seeded Argentinian Jose Acasuso, a two-time runner-up here, who advanced with a straight-sets victory over Oscar Hernandez 6-1 6-2.
