Roger Federer is set to begin his quest to win a sixth U.S. Open championship when he takes the court at Flushing Meadows on Tuesday afternoon. The world’s No.2 player is set to face Leonardo Mayer of Argentina at 3 p.m. ET.

The match will be broadcast on ESPN, and fans can also watch a free live stream online with WatchESPN. Federer is the second favorite behind Novak Djokovic to win the 2015 U.S. Open, and he’s expected to face a test from Mayer.

Federer, 34, dominated the U.S. Open in the mid 2000’s, winning the title each year from 2004-2008. The Swiss legend was defeated in the 2009 finals, and he hasn’t advanced beyond the semifinals since. Last year, Federer lost to eventual champion Marin Cilic in the semifinals.

Mayer has never advanced beyond the fourth round of a Grand Slam event. This year, Mayer won two matches at Wimbledon before being eliminated by Kevin Anderson in straight sets. At the French Open, Mayer defeated Jiri Vesely and Jerzy Janowicz, both ranked in the top 50, before falling to Cilic in the Round of 32. 

The 28-year-old is unseeded in the tournament despite being ranked No. 34. Federer is not taking Mayer lightly.

"I didn’t know he was unseeded," Federer said. "Total shock for me to see that I was going to play him, because he’s been seeded for some time now at majors. All of a sudden he’s not seeded here, so that’s why I think he’s a really tough draw."