Roger Federer said on Tuesday that he will spend this week at the Swiss Open testing his new larger racquet and will make a decision later on whether to use it in the run-up to the US Open and beyond.
The top seed, who is playing the ATP 250 clay event at altitude for the first time since he won it in 2004, will Thursday play his opening match after a bye against either German Daniel Brands or longtime friend Marco Chiudinelli.
Federer began testing a larger 98-square-inch racquet last week in Hamburg, reaching the semifinals before losing to number 114 Argentine qualifier Federico Delbonis.
He said he needs more time and matches to make a final decision on the prototype model.
"So far, I'm happy with this change," said the 17-time Grand Slam champion, "But I need many hours on the court to see if this is a good decision.
"I haven't yet taken the decision on whether to use it in the US (he begins his pre-US Open campaign in a fortnight at the Montreal Masters). I still need to think it over.
"There are players who have experienced" problems when they changed racquets, Fernando Verdasco and to some extent Novak Djokovic."