PORTLAND — The man from Down Under went up and over for the win.

Mitch Dening of the Portland Sea Dogs may not have been the most logical candidate to hit a walk-off home run, but on a warm Wednesday when the wind was blowing out, everyone was capable.

The Central Coast, Australia, native drove a fastball well over the right-field fence with one out in the bottom of the ninth inning for a 10-9 walk-off victory against the Binghamton Mets before a crowd of 6,809 at Hadlock Field.

Dening had his first three-hit game of the season (3 for 4, RBI single) on a day when the teams combined for 30 hits and seven homers, including a three-run blast by Will Middlebrooks of Portland.

But it was Dening’s fourth-inning walk that he credited for his strong showing.

“My second at-bat, when I was down 0-and-2 and worked it back to a walk, that really locked me in for the rest of the day,” Dening said.

Of his first Double-A walk-off homer, Dening said, “every at-bat I’m looking for a pitch to drive. On 2-and-0 I was really aggressive and tried to hit the ball out of the park and after (fouling a pitch off), I just told myself to relax. I got a fastball middle in, reacted and hit it out.”

Dening has seen his playing time increase due to injuries and absences of outfielders Alex Hassan and Chih-Hsien Chiang. He’s hit safely in eight of his last 10 games, batting at a .366 clip (11 of 30), with 11 RBI and four extra-base hits.

“Last year (in Class A Salem) he started slow and we were batting him ninth, and by the end of the year he was batting leadoff,” said Portland Manager Kevin Boles, who has managed Dening for three seasons.

“I’m not saying he’s going to do that again this year, but what we’re seeing him do is getting more consistent, more aggressive at the plate and using a new approach.”

Boles said in the past Dening had an exaggerated “bat wrap,” meaning Dening used a stance where the barrel of the bat was tucked behind his head.

With the slight pre-swing adjustment, he’s getting the barrel through the hitting zone quicker, Boles said, and that’s led to increased confidence.

When Portland scored four runs to take an 8-6 lead on Millbrooks’ sixth-inning homer that cleared the netting above the left-field wall, it looked like the Sea Dogs might not need any additional heroics. Instead the game continued to see-saw as it did all afternoon. Both teams’ pitchers were able to combine for only five scoreless innings.

Matt den Dekker hit his second homer of the day for Binghamton in the seventh to cut the lead to 8-7. The Sea Dogs strung together three hits in the bottom of the inning, with Jeremy Hazelbaker (2 for 4) driving in Jon Hee for a 9-7 lead.

Portland went to its best arm out of the pen, Blake Maxwell. The soft-throwing 6-foot-5 side-armer entered with a sterling 1.52 ERA and a team-best WHIP of 0.81. He promptly got touched for a double by Raul Reyes, a single by Brahiam Maldonado (3 for 4, homer), and an RBI single by Eric Campbell. Then Maxwell, who said he struggled to keep his fastball down in the zone upon entering the game, compounded his troubles by throwing away a sacrifice that allowed Maldonado to score the tying run and put runners at the corners with no outs.

“I’ve been doing this awhile. It’s not the first error I’ve made and it’s not the first time I’ve blown a save,” Maxwell said. “You just have to bear down and minimize the damage or everything will blow up in your face.”

Maxwell escaped further damage with two strikeouts and a shallow fly to right. In the top of the ninth, two infield hits and a grounder up the middle loaded the bases with one out, but he got a pop-up and comeback grounder to keep the score tied.

“That was huge what he was able to do, to hold it at 9-9 and not let the (error) get to him. That does not go unnoticed to us,” Boles said. “That’s his character. He doesn’t back down to anything.”

Ryan Khoury (3 for 4) also homered for Portland. Allan Dykstra hit a three-run blast for Binghamton.

Portland, which went 3-4 on the homestand, is in a virtual tie with Binghamton in the cellar of the Eastern Division. The Sea Dogs start a seven-game road trip at New Hampshire today.