Wellington: David Ferrer provided the class while Jack Sock played on his name with a victory giveaway as the ATP Auckland Classic semi-finalists sorted themselves out on Thursday.

Top seed Ferrer and number two Jo-Wilfried Tsonga moved into the final four with straight sets wins to join Sock and Roberto Bautista Agus who both took three sets to upset Kevin Anderson and John Isner respectively.

Sock recovered from a string of early unforced errors to beat Anderson 1-6, 6-4, 6-4 and celebrated the victory by starting what he says will become his win tradition: a sock giveaway.

“It feels great,” said the 23-year-old American who survived 14 aces by Anderson.

“He came out serving really well. He didn’t miss many first serves, didn’t let me get in the match.

“I knew it was going to be tough, but I was able to get in a little bit of a rhythm on returns and lucky enough to get a win.”

Sock, ranked 26th to Anderson’s 12, cutback on the error count after the disappointing first set and won the match on a service break and celebrated by throwing a sock into the crowd.

“I think with such a unique name that I have, we figured I might start a new tradition and give a sock away if I win,” he said.

“I did it real quick. I just turned around and threw it to some guy. I think I need to go out and play it up a little more, hold it up and see who wants it. Whoever wants a really sweaty sock can have it.”

Sock faces top seed Ferrer in the semi-finals after the Spaniard whipped Czech Lukas Rosol 6-3, 6-4.

Bautista Agut, beaten by Isner in the Auckland semi-finals two years ago, turned the tables with a 7-5, 2-6, 6-3 victory over the third seed.

“I had revenge today,” said the Spaniard, who is ranked 25th, 14 places behind Isner.

Bautista Agut will play Tsonga in the semi-finals after the Frenchman’s 7-5, 7-6 (7/4) win over Fabio Fognini.