Klahn gains another Challenger quarterfinal

   Bradley Klahn and Jeff Dadamo are beginning a spirited rivalry.
   Klahn, a wild card, edged Dadamo, a qualifier, 6-4, 4-6, 7-5 Wednesday in a battle of young, talented American left-handers in the second round of the $100,000 First Republic Bank Tiburon (Calif.) Challenger at the Tiburon Peninsula Club.
   They met for the first time as professionals, but Dadamo and Austin Krajicek of Texas A&M defeated Klahn and Ryan Thacher of Stanford 7-6 (4), 6-3 in the 2011 NCAA doubles final at Stanford, 50 miles south of Tiburon in the San Francisco Bay Area.
   Klahn, a 22-year-old resident of Poway in the San Diego area, reached a Challenger quarterfinal for the second consecutive week. He lost to eventual champion James Blake in that round 7-6 (5), 7-6 (4) in the $100,000 RelyAid Natomas Challenger in Sacramento.
   Dadamo, 23, of Tampa, Fla., fell to Thacher in the first round of qualifying in Sacramento.
   Steve Johnson of Orange, Calif., dismissed former USC teammate Robert Farah of Colombia  6-3, 6-3 in a rematch of the Aptos (Calif.) Challenger in July. Johnson, who also won that encounter, captured the last two NCAA singles titles before completing his eligibility. Farah won the 2008 NCAA doubles title with Kaes Van't Hof.   
   Also reaching the Tiburon quarterfinals were third-seeded Bobby Reynolds, a semifinalist last week in Sacramento, and seventh-seeded Denis Kudla of Arlington, Va. Reynolds will play Klahn, and Kudla will face Johnson.
   The second round will be completed Thursday. Top-seeded Benjamin Becker and the second-seeded Blake will meet 20-year-old U.S. prospects Jack Sock and Daniel Kosakowski, respectively. Kosakowski reached the Sacramento semifinals.