TRENTON, N.J. – Sometimes a couple of mistakes are all it takes to continue a losing streak.

That’s what happened to the Portland Sea Dogs on Monday night as they committed two costly errors and ran into some strong Trenton relief pitching while dropping their fourth straight, 5-3 at Waterfront Park.

Oscar Tejeda’s fielding error at second in the fourth cost Portland a pair of runs, and Trenton got another when third baseman Will Middlebrooks bobbled a grounder in the fifth.

“We played hard but a couple of miscues on defense ended up costing us a couple of runs tonight,” Sea Dogs Manager Kevin Boles said.

Asked how to snap out of the skid, Boles said, “You stay positive and work harder. You keep grinding it out because it’s a long season and we’re going to keep working. We need to take care of our business and play a little bit of a cleaner game.”

Chih-Hsein Chang homered and Jorge Padron had three hits for Portland (8-13), but the rest of the Sea Dogs managed four hits off four pitchers. The Thunder bullpen pitched four scoreless innings, allowing one hit and striking out seven.

Among Trenton’s relievers were former Red Sox outfielder Brian Anderson and Tim Norton, a native of Franklin, Mass.

Anderson, who homered twice in 17 at-bats with the Red Sox in 2009 in a seven-year major league career as an outfielder, is in his second season trying to reincarnate himself as a relief pitcher. He pitched a scoreless eighth, striking out the side.

“He has an aggressive approach, he goes right after you,” Boles said. “There’s no fear. It’s a quality arm. It looks like he has a pretty good delivery.”

Norton continued his fine season, pitching two perfect innings to lower his ERA to 0.71 (one run per 122/3 innings pitched.) He struck out three and has 19 strikeouts against four walks. Norton, who turns 28 May 23, broke camp healthy for the first time in his career.

“He’s a guy you have to get to early because if he gets ahead, he has the pitch to finish,” Boles said.

The Sea Dogs were playing from behind all game. After Trenton took a 2-0 lead in the second, the Sea Dogs got a run back in the third on Alex Hassan’s sacrifice fly that scored Chang. It was Hassan’s 16th RBI, tying him with Tim Federowicz for the team lead. Hassan doubled in the fifth, his eighth of the season, and has hit safely in 19 of Portland’s 21 games. He finished 1 for 2, raising his EL-leading average to .415.

The Thunder took a three-run lead in the fourth thanks to a pair of unearned runs, on RBI singles by Addison Maruszak and Dan Brewer. The runs were unearned as Tejeda couldn’t get his glove down on Corban Joseph’s leadoff grounder.

Chang’s homer over the high scoreboard in right-center, his first of the season after hitting 11 last year, brought Portland within 4-3.

“He took a real good swing,” Boles said. “He showed plus bat speed tonight. It was really good to see. He took a real good pass at that ball. It was fun to watch.”