SAN FRANCISCO — It’s been three months since the Giants took sole possession of first place in the National League West with a four-game win streak that began with three straight victories over the Dodgers.

The lead grew to 4.5 games by late June, shrunk to 0.5 games in early July, increased to a season-high 5.0 games in mid-August and finally fell back to the narrowest of margins, 0.5 games on August 31. Regardless of how well or how poorly the Giants played, though, they could always count on waking up in a better position than their rivals.

On a chilly Wednesday night at Oracle Park, that lead disappeared.

A Giants team that’s played its worst baseball of the season this week extended its losing streak to four games with a 5-2 defeat to the NL Central leaders, the Milwaukee Brewers, and fell 0.5 games behind a Dodgers (85-49) club that came from behind to beat the NL East leaders, the Atlanta Braves.

“We kind of all knew at some point we were going to get tested, it was kind of too good to be true,” starter Kevin Gausman said. “The way that we were rolling, at some point I think all of us kind of knew we were going to have a four or possibly five game skid at some point. But you know, it’s incredible, if you think about it, to get to this point of the season and we’ve only had one of those.”

Right fielder LaMonte Wade Jr. gave the Giants (84-49) a chance to tie the game in the eighth inning against Brewers righty Jake Cousins with a 402-foot flyball to deep right center field, but the ball sailed off the right field wall and left Wade standing at second base with a double.

Wade’s blast would have been a home run in all 29 other major league parks, but he happened to hit it at Oracle Park, where flyballs to right center field go to die. After an Austin Slater strikeout and a Thairo Estrada groundout ended the scoring threat, the Giants watched Brewers center fielder Lorenzo Cain lead off the ninth with a 391-foot solo home run that narrowly cleared the left field wall.

The Brewers tacked on another run, but a struggling Giants offense wasn’t a match for Milwaukee closer Josh Hader anyway. Less than three weeks after holding a 5.0-game lead over the Dodgers, the Giants have watched it disappear and will turn to their emerging ace, Logan Webb, on Thursday to get the team out of a rut.

“Anytime you have a little losing streak, it’s not fun,” catcher Buster Posey said. “You know this group has showed an ability to bounce back throughout the year and that’s just what you have to believe that you’re going to do. We’re playing some been playing some really good teams, some good pitching and that’s going to continue, and hopefully continue in the playoffs as well.”

The Giants’ first half ace, Kevin Gausman, turned in a solid start as he held the Brewers to two runs over five innings, but few other Giants played well as the club lost Wednesday’s game by making the type of mistakes they’ve typically feasted on this season.

The sequence that burned San Francisco came with two outs in the seventh inning as reliever Dominic Leone issued a walk to the Cain, the No. 8 hitter, before pinch-hitter Jackie Bradley Jr. hit a chopper to the right side of the infield that should have ended the inning. Instead a failed exchange from first baseman Brandon Belt to Leone covering the base allowed Bradley to reach as Belt’s toss was past the pitcher’s outstretched arm.

With runners on the corners and two outs, Gabe Kapler turned to left-hander José Álvarez to face Milwaukee leadoff man Jace Peterson. After falling behind in the count 2-0, Álvarez battled back with consecutive strikes before Peterson laced a go-ahead single into left field, which gave the Brewers a chance to put the game in the hands of their best relievers.

A Giants offense that entered Wednesday’s game with a combined three runs in its last three games could chalk up some of its recent slump to facing a pair of the top arms in the National League in Brewers starters Corbin Burnes and Brandon Woodruff, but explaining the struggles away got a lot tougher on a night when Milwaukee lefty Brett Anderson exited after two innings due to a shoulder bruise suffered on a Brandon Crawford line drive that forced the Brewers to use several of their lower-leverage relievers.

With the Giants down a pair of starting pitchers, Kapler made the surprising decision to pinch hit for Gausman after the right-hander completed five innings of two-run ball. Gausman was excellent for most of his outing as he racked up seven strikeouts including three with his splitter in the first inning, but the Giants’ offense looked lifeless and Kapler bet Alex Dickerson could ignite a rally.

Dickerson helped the decision pay off with a double to left field that preceded a double into the right field gap from Bryant that snapped an 0-for-15 stretch with runners in scoring position for the Giants that began on Tuesday.

After reliever Justin Topa threw three consecutive balls to Belt, the Brewers elected to intentionally walk the Giants’ first baseman to bring Posey to the plate. Despite entering the plate appearance with four hits in his last 39 at-bats, Posey found a way to tie the game by poking a softly-hit single past first baseman Rowdy Tellez.

The two runs were the only runs the Giants scored, as they’ve now been held to five runs and just one home run, a Belt solo shot on Tuesday, during their four-game skid. Perhaps the only good news for San Francisco is that an opportunity to gain ground will soon present itself as the Dodgers are off Thursday before traveling to Oracle Park for a pivotal three-game set that begins Friday.

“It’s gonna be a battle,” Gausman said. “It’s going to come down to probably the last five, six games or so, so I think we’re just focused about ourselves more than anything right now.

The Giants can regain control of the division, but if their struggles persist, they could find themselves in a much deeper hole than they recently envisioned.

“I think now is the right time to really show a sense of urgency, continue to dig in on our process, but also not to have any panic,” Kapler said. “There’s no need for that.”