Since returning from the World Cup, Chris Wondolowski has done all he can to power the San Jose Earthquakes offensively, with seven goals and five assists in 10 matches.

Unfortunately for the Quakes’ captain, his side has not been able to keep hold of the leads he keeps helping to create.

Sunday afternoon proved no different for San Jose, who saw 2-0 and 3-2 advantages slip away in what ended as a 3-3 draw against the Portland Timbers at Providence Park.

“I don’t know what to say,” Wondolowski told reporters after the match. “I’m a bit speechless. To a man in the locker room, we know that it’s just not good enough right now. It hasn’t been good enough all season. We keep finding ourselves shooting ourselves in the foot. It hurts.”

Those were the fourth and fifth leads that the Quakes have let slip away in a winless streak that has now stretched to six painful games. In addition to Sunday’s finish, San Jose tied the LA Galaxy on Aug. 8 (Gyasi Zardes and Omar Gonzalez finding equalizers) and drew Real Salt Lake last weekend (Javier Morales converting a penalty to negate Sam Cronin’s early strike).

The Quakes (6-10-9) -- still mired in eighth place in the Western Conference on 27 points -- don’t have long to dwell on the missed opportunities, however, as their road trip continues north of the border with a midweek match at Vancouver (Wednesday, 10 p.m. ET, MLS Live).

“We need to stay positive,” Quakes coach Mark Watson said. “We’re disappointed. We’ll look at the video, and look at the things we need to improve upon. We’ll get rested up and go again Wednesday in Vancouver. I think we all know we’re needing wins right now. I think everyone’s well aware of that. We’ll go over the game, try to learn from some of the mistakes we made in letting a team back into the game and we’ll push forward.”

The Quakes had done well to withstand Portland’s brutal early pressure in a sustained 20-minute blitz to open the match and respond with Wondolowski’s strike off Shea Salinas’ rebound in the 21st minute and Cordell Cato’s sumptuous finish in the 48th. San Jose redoubled their efforts after the Timbers finally broke through with second half tallies by Alvas Powell and Liam Ridgewell, with Wondolowski sneaking between Ridgewell and Pa Modou Kah to head home Salinas’ left-wing cross in the 85th minute -- only to see Kalif Alhassan drag the hosts back a minute later.

“Yeah, we went up 3-2, but we let in three goals in one half,” Wondolowski said. “That’s not good enough. . . . That’s why it feels so gutting to come away with a tie. We need wins at this point.”

The lapses wasted Wondolowski’s 15th career multi-goal performance in MLS play, chipping away at what had been a near-certainty for the Quakes. San Jose was 11-0-2 when Wondolowski had two or more goals from 2010 through last season; this year, they’re just 0-1-1, having lost 3-2 at Vancouver on May 3 despite a brace from their captain.

“His second goal was just good movement, really,” Watson said of Wondolowski. “He’s in between the center backs. He wanted that indecision from them. That’s just Wondo. He can be quiet for large parts of the game, but he can strike at any time. It’s disappointing that we scored three goals and didn’t get the result.”