Pablo Andujar has eased past an exhausted Janko Tipsarevic to reach the third round of the Cincinnati Open.
The 40th-ranked Spaniard fell behind in the first set but went on to secure a straight-sets 6-4 4-1 victory.
Tipsarevic moved into a 4-2 lead in the first set but soon came apart. The Serbian lost eight of the next nine games and bowed out of the competition.
Andujar held seven of eight service games and a final hold at 3-1 convinced Tipsarevic to retire, citing heat exhaustion.
The 26-year-old will next take on Marin Cilic, who triumphed over Jesse Levine earlier today.
