Roger Federer lifted his clay-court game when it mattered to beat Arnaud Clement 7-6, 6-2 and book a semi-final place at the Estoril Open on Friday.
Federer's woes on the surface looked in danger of continuing when he lost the first two games of the quarter-final but he gradually improved to see off the Frenchman with something of a flourish.
"At the end I tried some drop shots, which was very good for me, to know I can hit them," the world number one told reporters.
"I know I have a great feel (for them), but it's important to hit them in a match in a tough situation and use the right moment to do so.
"So that was something more fun for me, it gives me more confidence leaving the court today," he added.
Federer, who lost his first match of the clay-court season in Rome, said he is happy with wins of any sort on the surface as he prepares to defend his French Open title.
He next faces champion Albert Montanes after the Spaniard beat Uruguayan Pablo Cuevas 6-4, 6-3.
The other semi-final will be between Spanish fifth seed Guillermo Garcia-Lopez and local hero Frederico Gil, who beat compatriot Rui Machado 4-6, 7-6, 6-3.