Sierra High’s Anna Cardenas defeated Christine Kim in the No. 1 singles encounter Thursday, but the Timberwolves couldn’t put away other tightly-contested matches in a 7-2 defeat against second-place Oakdale.Sierra (5-8) could have come away with a big upset, as four of the matches, including Cardenas’, were settled in third sets. Cardenas upended Kim 6-4, 6-7 (5-7), 6-2.