Manteca High’s string of shutouts ended Monday, and it came at the worst possible time.

Host Oakdale is guaranteed at least a share of its first-ever Valley Oak League championship after a well-contested 2-1 win over the Buffaloes, who needed to win out this week to reserve a spot in the Sac-Joaquin Section Division-IV playoffs.

With Oakdale (10-2-1, 16-2-4 overall) winning, Sierra and East Union are assured the other two playoff spots.

Manteca (7-5-1, 13-7-2) mounted a valiant charge toward a possible berth over the second half of league play, starting with a 3-1 revenge win over Kimball on April 11.

Since then, goalkeeper Jimi Guibor and the defense kept the sheets clean for four straight matches and hung tough for almost 70 minutes at Oakdale Monday.

Oakdale’s Jill Kahler connected with Bryanna Welch in the 68th minute to break the ice, and Kahler recorded her own goal four minutes later.

On what ended up being the final play, Manteca striker Sammie Morris scored on a penalty kick to cap the score.

While it’s a rough way for the Buffaloes to have their postseason aspirations end, they did well to put themselves in position to vie for one of three berths. They would have had to have beaten two playoff qualifiers this week, however. East Union visits Manteca for the regular-season finale Wednesday.

“That’s all you can ask for, is to be able to control your own destiny,” Manteca coach Justin Coenenberg said. “We had a chance because we’ve been playing so well. We came close, but I’m not disappointed at all.”

Manteca had two big chances to take the first lead, but a breakaway sequence and a point-blank volley both resulted in shots directed to Oakdale goalie Morgan Kinyon.

Guibor battled through a hip injury sustained late in the first half and finished with nine saves.

“She was not moving very well in the second half, but she still made some great saves,” Coenenberg said. “We came out and really took it to them in the first 30 minutes of the second half, but we’re not real deep defensively and I think we were just worn down in the back.

“I thought we were dominating, but that first goal really broke our spirits.”

At Daniel Teicheira Memorial Stadium, Stephanie Vanni netted four goals — two off head shots — and Joanna Ortiz scored once while assisting three others.

Defenders Sydnee Koscielecki and Donna Ochoa each added a goal, as did Jacqueline Revives.

Sierra (8-1-4, 13-2-6) still has a shot to share the championship, but the Timberwolves would need one of the league’s worst teams, Sonora, to upset first-place Oakdale Wednesday.

“We had our shot,” Sierra coach Manuel Pires said. “The door was open for a little bit and we didn’t take care of business, so now the focus is on the playoffs.”

At Dino Cunial Field, the Lancers put themselves in great position to capture one of the playoff berths by beating Kimball. The match was originally scheduled for last Wednesday.

Megan Howley scored twice and had two assists in her first game back from an ankle injury, which had her sidelined for the first 12 VOL contests.

Freshman Regina Dias had a hat trick, and Kayla Lamont recorded the first goal off of Stephanee Sabala’s cornerkick.

At Dino Cunial Field Monday, the Squires took 29 shots to Sonora’s 1 with two goals apiece coming from Rose Wood, Angelique Galvan and Crystal Munoz.

Taylor Baun, Taylor Rose and Sam Thurmon contributed one each.