MADRID, April 24 — Spain’s Rafael Nadal said on Wednesday that he is not sure if he will be able to play at next month’s French Open after pushing through the pain barrier in his comeback from injury.

The 37-year-old, a 22-time Grand Slam champion, said that he is far from being in top form and that he is only playing against American Darwin Blanch in the first round of the Madrid Open on Thursday as a personal sacrifice.