Puerto Rican qualifier Monica Puig shocked second seed Caroline Garcia to reach the WTA Connecticut Open semi-finals, while three-time winner Petra Kvitova was forced to retire.

Reigning Olympic champion Puig stunned Garcia 7-5 1-6 6-2 in New Haven on Thursday to advance to her first semi-final of the season.

A hip injury has hampered Puig but the 24-year-old will now face Carla Suarez Navarro in the final four of the tournament.

Suarez Navarro moved through to the next round after third seed Kvitova retired due to a shoulder injury.

Kvitova took a medical timeout after losing the first set 6-3 and she was unable to continue against the Spaniard.

Julia Goerges and Aryna Sabalenka will contest the other semi-final at the Connecticut Open.

German fifth seed Goerges defeated Ekaterina Makarova 6-4 6-2 thanks to 29 winners, while Sabalenka topped Belinda Bencic 6-3 6-2.