Sophomores Bradley Klahn and Ryan Thacher won two matches on Thursday to advance to today’s quarterfinals at the Pac-10 Championships in Ojai, Calif.

Klahn, Stanford’s top singles player and the No. 2 seed in the tournament, defeated Oregon’s Nico Bjerke 6-2, 6-1 in the first round and UCLA’s Max Ta Ba Truong 4-6, 7-6 (10), 6-2 in the second round to advance. Thacher, Klahn’s doubles partner and the No. 3 seed in the tournament, eased into the quarters with two easy victories, a 6-1, 6-3 win over Oregon’s Rick Mortera in the first round and a 6-3, 6-2 win over Washington’s Martin Kildahl in the second round.

Junior Alex Clayton and senior Richard Wire both fell in the second round on Thursday. Clayton, the No. 4 seed, beat Arizona’s Borja Malo 6-4, 6-3 before being upset by UCLA’s Matt Brooklyn 6-3, 4-6, 6-2. Wire beat Arizona’s Ravid Hazi 6-4, 6-4 and then lost to UCLA’s Nick Meister, who is the No. 7 seed.

Thacher and Meister will match up in the quarterfinals today, while Klahn will take on unranked Peter Lucassen of USC.

Freshmen Walker Kehrer and Matt Kandath cruised with straight-sets victories to reach the quarters of the Invitational division.

Doubles play will begin today as well, with Klahn and Thacher as the No. 2 seed. Clayton and Wire are also competing, as are Kandath and fellow freshman Denis Lin. Kandath and Lin will face off with the No. 1 seed duo of Robert Farah and Steve Johnson of USC. Kehrer and junior Greg Hirshman have a bye into the quarters of the Invitational division.