Updated

MELBOURNE (Reuters) - U.S. Open champion Juan Martin Del Potro recovered from a set down to advance to the third round of the Australian Open after surviving a marathon battle against American James Blake Wednesday.

The fourth-seeded Del Potro had been in danger of becoming the highest-ranked men's player to be eliminated before he rallied from a break down in the fifth set to take the match 6-4 6-7 5-7 6-3 10-8 in four hours, 17 minutes.

The 30-year-old American, who twice had treatment on his right knee that had to be strapped during the match, had held a 2-0 advantage in the final set though the tall Argentine managed to fight back to put the match back on serve.

Del Potro had the opportunity to serve for the match in the 12th game only to be denied by Blake before he finally took the advantage again in the 17th and sealed it with a massive serve that Blake was unable to return on the next game.

(Reporting by Greg Stutchbury; Editing by John O'Brien)