Carlos Alcaraz was forced to work hard to beat underdog Ethan Quinn to reach the Barcelona Open last 16 on Tuesday.

The world number two was a break down in the second set against Quinn, ranked 126th in the world, before fighting back to win 6-2 7-6 (8-6).

After saving five break points and breaking Quinn twice in the opening set, Alcaraz was pushed much harder by the 21-year-old American in the second.

The players exchanged breaks on three occasions and Alcaraz, 21, had to save a set point in the tie-break before finally winning through.

"I made some mistakes, I found it hard to maintain my level, but I am happy to have solved the problems that came in the second set, and to end up winning in two sets," Alcaraz told TVE.