Dirk Nowitzki sees Tommy Haas win

After going to two Mavericks games this week to see his friend and countryman perform, Tommy Haas did the entertaining Friday and Dirk Nowitzki did the spectating.

With Nowitzki perched in a box behind one baseline, German veteran Haas treated his pal to a vintage performance to secure a spot in the semifinals of the $125,000 Dallas Tennis Classic, pounding out a 6-4, 6-4 victory over Gilles Muller of Luxembourg at the Four Seasons Resort and Club in Las Colinas.

Formerly No. 2 in the world rankings but down to No. 169 after myriad injuries at age 33, Haas has to the deal with the tournament's Cinderella next. Canadian qualifier Frank Dancevic is Haas' opponent in Saturday's semis after Dancevic knocked off top-seeded Marin Cilic of Croatia.

Nowitzki stuck around for that match, too, and witnessed the upset of the week as Dancevic claimed a 7-6 (7-5), 7-6 (7-5) victory over the 24th-ranked player in the world. Dancevic is ranked only 175th, but he's won five straight matches in this ATP Tour Challenger stop when you include the two wins he needed just to get into the 32-player main draw.

Immediately after Haas' victory, though, Nowitzki first accepted Haas' invitation to head for an outside court at the Four Seasons to hit a few balls. Handball and tennis were the two sports Nowitzki focused on as a youth in Germany before devoting his energies to basketball, and he once faced Haas in a junior doubles match in Bavaria. On this occasion, Nowitzki shared a side with German Davis Cup captain Patrick Kuhnen -- who is traveling in the States with Haas this month -- and hit with Haas for about 15 minutes after his match, attracting a flurry of fans scrambling for photos and video of the Mavs' star with a racket in his hand.

Saturday's other semifinal will pit another German -- 113th-ranked Bjorn Phau -- against Russia's Igor Andreev.

Formerly ranked as high as 18th in the ATP Tour rankings, Andreev posted a 6-3, 3-6, 6-2 victory over eighth-seeded Lukas Lacko of Slovakia. Phau advanced with a 6-4, 7-6 (7-4) win over fourth-seeded Robin Haase of the Netherlands.

Friday's results ensured that the champion of the inaugural Dallas Tennis Classic will be unseeded. Saturday's and Sunday's matches will be televised on TXA 21.