SEATTLE -- Milwaukee manager Craig Counsell was spending his 46th birthday much as he spent most of the 2016 baseball season -- that is, watching his Brewers stumble toward another disappointing finish.

Trailing by five runs after five innings and by three going into the ninth, the Brewers wound up giving Counsell the kind of gift worthy of celebration Sunday.

A four-run ninth inning that included two home runs, several defensive mistakes and a routine fly ball that resulted in the game-winning RBI all added up to a 7-6 win over the Seattle Mariners.

"That's a good one, a really good one," Counsell said after his team snapped its season-worst, six-game losing streak. "A good birthday present, for sure."

Milwaukee pinch hitter Scooter Gennett delivered an RBI single in the top of the ninth, capping off a four-run frame.

For the mistake-prone Mariners, who are in the thick of the American League wild-card hunt, the loss felt more like a cake to the face.

"It's disappointing, no doubt," manager Scott Servais said after his team failed to pick up a game on the Baltimore Orioles. The Mariners still trail by one game in the AL wild-card race. "It's been a really good stretch at home. We've got to finish (the game), got to close it out, and we just didn't do it today. There were some plays to be made there."

Gennett's lazy fly ball, which fell between Seattle left fielder Norichika Aoki and center fielder Leonys Martin on a night when the Mariners misplayed at least two fly balls, brought in Domingo Santana from second base to give the Brewers (53-70) their first lead of the game -- and Milwaukee's first lead of a seven-game road trip to Wrigley Field and Safeco Field.

Aoki said after the game that he thought he "felt the presence" of Martin, only to realize upon taking his eyes off the ball that Seattle's center fielder was not going to make the play. The fact that Aoki misread an earlier fly ball that resulted in a Keon Broxton home run added to Aoki's frustration.

"There will probably be games like this in the future," Aoki said through an interpreter. "The important thing is to turn the page and not repeat the mistake you made."

Broxton had a pair of solo home runs, including a leadoff shot that sparked the four-run ninth. Broxton entered the Seattle series with three home runs on the season, then hit three more in three games against the Mariners.

Seattle (66-57) stormed out to a 6-1 lead but gave all of it back after the fifth.

Ryan Braun's two-out, two-run double in the sixth cut the deficit to 6-3.

On an afternoon when Seattle closer Edwin Diaz was getting a break for the second game in a row, Tom Wilhelmsen filled in and promptly gave up two home runs.

Broxton's leadoff shot cut the Seattle lead to 6-4, and then Chris Carter added a one-out, two-run shot that barely cleared the wall in left to tie the score 6-6.

Mariners right fielder Shawn O'Malley, a defensive replacement in the ninth, appeared to catch the ball at the top of the fence before collapsing on the warning track. While he writhed around in pain, the players waited for an official call from the umpire. Several seconds passed before first base umpire Chad Fairchild motioned that the ball went over the fence, at which point Carter, who was standing on second base, began his home run trot.

"That's a great feeling," Carter said of finally seeing Fairchild signal for the home run. "After a rough road trip, to end up with a win like that feels great."

Veteran reliever Vidal Nuno came on to relieve Wilhelmsen after a Santana single, and the left-hander wasn't much better. Nuno gave up back-to-back singles, including the RBI bloop off the bat of Gennett.

Seattle got a leadoff single from Ketel Marte in the bottom of the ninth, but he ended up getting stranded on second after three consecutive popups. Robinson Cano's pop fly to short center field ended the game while earning Milwaukee reliever Tyler Thornburg (5-4) the win.

Wilhelmsen (2-4) took the loss after allowing four runs on four hits while retiring just one of the five batters he faced.

"It's not often that you can say any one person won a game in this line of work, but you can say you definitely lost a game," Wilhelmsen said. "That's what I did today. We've been playing well, so it's definitely disappointing. But you just have to come back (Monday) and kick some butt."

Servais said he decided before the game that he was not going to use Diaz, his usual closer, under any circumstances. He wasn't second-guessing the decision afterward.

"I thought we were in a good spot," Servais said. "Tom Wilhelmsen has given us everything he's got this year. It just wasn't his day."

Seattle starter Ariel Miranda allowed three runs on four hits over 5 2/3 innings in his third start since being acquired from the Baltimore Orioles in a deadline deal.

Mariners right fielder Seth Smith had a pair of hits while driving in two runs. Robinson Cano added a pair of RBIs on groundouts.

Aoki, Nelson Cruz, Marte and Martin also had two hits apiece for the Mariners, who lost for only the fourth time in 16 games.

NOTES: The Mariners expect to get LHP James Paxton back into the rotation Thursday. Paxton took a line drive off his pitching elbow on Aug. 7 and has been battling a bruise that eventually landed him on the 15-day disabled list. ... Milwaukee's six-game losing streak entering Sunday was the team's longest of the season. The last time the Brewers endured more losses in a row was last September, during an eight-game losing streak. ... Brewers GM David Stearns told the Milwaukee Journal Sentinel before Sunday's game that LHP Chris Capuano, a 38-year-old reliever who has been battling elbow problems since late May, won't pitch again this season. ... Milwaukee wrapped up a seven-game road trip Sunday. The Brewers begin their 10-day homestand with a Monday game against Colorado. The Mariners begin a three-game home series against the Yankees on Monday night.