Santiago Giraldo through after Philipp Kohlschreiber withdrawal

Santiago Giraldo has reached the semi-finals of the Barcelona Open after 10th seed Philipp Kohlschreiber retired a set and a game down in their last-eight meeting.

The tournament has been thrown wide open following the shock elimination of Rafael Nadal, but Kohlschreiber could not capitalise against a lower-ranked opponent.

Even before his injury, the German was struggling with world number 65 Giraldo, who took his second break point to move into a 4-2 lead in the opener, before Kohlschreiber put the match back on serve.

Giraldo's immediate break in response, though, earned him the first set and he looked to be taking full control of the contest when he won the first three games of the second, only for Kohlschreiber to rally.

Just when it appeared as though the former Wimbledon quarter-finalist was turning things round, as he levelled the set at 3-3, he withdrew from the encounter with an unknown injury.

Giraldo will play Nicolas Almagro, who beat Nadal earlier on Friday to prevent the Spaniard winning on Barcelona's clay for the ninth time in 10 years, in the semi-finals of the tournament.