Anything can happen on an indoor hard court when a free-swinging underdog with plenty of power squares off against a favorite rusty from injury.  And anything did happen on Friday in Rotterdam, when Ernests Gulbis and Marin Cilic recorded surprisingly routine victories over top-eight opponents Juan Martin del Potro and Andy Murray.

A man who often rises to the level of his competition, Gulbis owns victories over Roger Federer and Novak Djokovic, while he has thrust Rafael Nadal to the brink more than once.  February marked his resurgence last year, featuring a 13-match winning streak. Gulbis seemed to have recaptured his fondness for February already when he knocked off Australian Open quarterfinalist Grigor Dimitrov on Thursday.  That was a signal of what lay ahead in a dominant performance against Del Potro.  Gulbis hit as many aces (12) as he lost service points, and he saved the sole break point that he faced in the match.  Del Potro, the defending champion, did not play poorly despite the straightforward 6-3 6-4 scoreline.  He maintained a high first-serve percentage and saved seven break points.  But he faced much greater pressure on serve, which separated the two men in the end.

Toppled by the identical scoreline, world No. 6 Andy Murray followed No. 4 del Potro out of the tournament just a few hours later.  Few would identify indoor hard courts as Murray's surface of choice, despite his chronic success on them.  By contrast, Marin Cilic arrived in Rotterdam fresh from claiming his fourth title on the indoor hard courts of Zagreb, his home tournament.  That momentum spurred Cilic to his second victory over Murray, saving all four break points that he faced.  Each man dominated behind his first serve, losing just four points behind it.  Cilic won just seven more points than Murray did overall, so the match was closer than its scoreline and 71-minute length suggested.  Whenever he faced a dangerous situation, however, he found the accurate first strikes that he needed to survive it.  Cilic also broke Murray early in each set, so he had the luxury of playing from ahead for most of the match.

Both underdogs should feel elated by their upsets, but neither favorite should feel disheartened.  Del Potro returned to action this week after a recent consultation at the Mayo Clinic regarding a wrist injury, so merely appearing in Rotterdam marked an encouraging sign for the spring.  While Murray's back surgery last fall now lies several months behind him, he has played only three ATP tournaments since then.  Like his coach, Ivan Lendl, the reigning Wimbledon champion recognizes that the road back to his best form may take several twists and turns. 

In the absence of Del Potro and Murray, third seed and world No. 7 Tomas Berdych becomes the favorite to claim the Rotterdam title over the weekend.  But a Saturday semifinal will force him to solve Gulbis, who has defeated Berdych before.  This tournament now seems open for any man to win.