By Erik Gudris

(July 19, 2013) -- Roger Federer raised a few eyebrows with his fashion choices this evening at the German Tennis Championships. But it was the four-time champion and his high level of play at the end of his quarterfinal versus Germany's own Florian Mayer that got everyone's attention.

Mayer, though currently ranked outside the top 40, possesses an unorthodox game of power and spin that many thought could pose a problem for Federer despite the Swiss star never having dropped a set to the German in four previous meetings. Aggressive returning from Federer allowed him to seize a close first set tiebreak seven points to four.

Federer, perhaps to fight off the chilly night air, donned a black sweater vest in the second set. But it was Mayer who heated his own game to take an early break of serve with a roundhouse forehand winner. Mayer soon jumped out to a 5-1 lead. Though Federer looked poised to perhaps pull even with the German down the stretch, it was Mayer who held on to take the set 6-3.

Both men traded multiple breaks of serve throughout the final set with neither man able to hold on to any momentum. Federer looked more at ease with his new larger racquet, especially on his backhand side when forced wide or when hitting high balls near his shoulder. But he wasn't able to finish off Mayer as quickly as he would have liked due to the German staying with Federer in many of their longer rallies.

After holding serve to stay in the match at 4-5, Federer ripped a crosscourt forehand to set up three break points. Federer converted one with another forehand winner to go up 6-5.

From there, Federer kicked into high gear and served out the 7-6(4), 3-6, 7-5 victory.

Next up for Federer in the semifinals is Argentinian qualifier Federico Delbonis who survived against No. 14 seed Fernando Verdasco of Spain.

After squandering two separate match points against Delbonis in their quarterfinal, Verdasco left the court before the start of the third set. According to TennisTV.com staff, Verdasco went into the player's locker room and punched a locker in frustration at having not won the match.

Verdasco needed a medical time out to have his hand treated during the early stages of the final set. Having been warned earlier in the match for smashing his racquet, Verdasco was later given a point penalty for ball abuse that gave Delbonis the game for 4-3.

Delbonis held serve and then went on to win the over three hour contest 6-7(5), 7-6(8), 6-4.

Almagro and Fognini to Face Off in Semis

Earlier in the day, Spain's Nicolas Almagro got revenge on defending champion Juan Monaco who beat Almagro in last year's semis. In just under two hours, Almagro saw off Monaco  4-6, 6-0, 6-3 to reach the third Hamburg semi of his career.

Italy's Fabio Fognini continued his fine run from last week that saw him win his first ever ATP title in Stuttgart.

Fognini, now on an eight match winning streak, earned a mild upset win over No. 2 seed Tommy Haas 6-2, 6-4 in 82 minutes.

Almagro leads the head to head versus Fognini 3-1.

(Photo Credit: AP)