OAKLAND -- The ability of Liam Hendriks to bring stability to the ninth inning has been a major reason the A’s find themselves in control of a playoff spot this late in the year. But Monday night saw a rare Hendriks hiccup.

After Khris Davis' RBI single broke an eighth-inning tie, Hendriks was unable to make a one-run lead hold up as he surrendered a pair of runs in a 6-5 loss to the Royals at the Coliseum. It was just his second blown save when entering a game in the ninth this season.

• Box score

Hendriks’ downfall came down to two pitches: A 2-0 fastball left over the heart of the plate that was crushed by Brett Phillips for a game-tying solo home run, and a first-pitch fastball low in the zone that was golfed by Adalberto Mondesi for a go-ahead RBI double just two batters later.

“The ball was down the middle to Phillips, and Mondesi hit a good pitch the other way for a double,” A’s manager Bob Melvin said. “[Hendriks] has been absolutely fantastic for us. Every now and then, you’re going to blow a save.”

On a night when the Rays and Indians -- the two clubs hot on the A’s trail for the top American League Wild Card spot -- were idle, the loss shrunk Oakland’s lead for the top spot over Tampa Bay to just one game with 11 to go in the regular season. The loss also snapped a six-game winning streak for the A's.

• Wild Card standings

Hendriks wasn’t the only pitcher who struggled to hold a lead.

A high pitch count led to an early departure for A’s starter Tanner Roark, who was pulled with two runners on and two outs in the fifth at 110 pitches. Melvin went to Jake Diekman for a lefty-lefty matchup against Alex Gordon, but the favorable matchup backfired when Gordon lined a game-tying two-run single.

Roark escaped a bases-loaded jam the previous inning by striking out three batters in a row and felt strong enough to finish off the fifth, but he understood the reasoning behind Melvin’s move.

“I wanted to stay, but it’s that time of year where we’re right on the cusp of things. I don’t blame him. I threw a lot of pitches,” Roark said. “I just have to do more of getting early contact with a good defense behind me.”

Roark was charged with four runs on seven hits over 4 2/3 innings and his eight strikeouts were the most he’s recorded in a start since joining the A’s.

Semien surpasses a legend

Melvin has stated his case for Marcus Semien to garner AL MVP votes on multiple occasions. With a record-breaking season that seemingly continues to get more impressive each day for the shortstop, that idea may no longer seem far-fetched.

With Rickey Henderson taking in the action Monday night from a seat right behind home plate at the Coliseum, Semien etched himself in Oakland lore, adding to an early A’s lead in the second inning with a two-run blast off Royals starter Glenn Sparkman. The homer was Semien’s 31st of the year and his 29th when batting in the leadoff spot, surpassing Henderson’s club record of 28 homers from the leadoff spot in 1990.

“I saw Rickey today right behind home plate,” said Semien, who was unaware of the record until being told after the game. “I thought it was pretty cool that he was sitting back there and checking us out. He’s always helping us in the clubhouse and just hanging out with us. He’s an MVP and Hall of Famer.”

Making the record a little more meaningful for Semien is the Bay Area connection the two share, with Henderson an Oakland native and Semien having grown up in nearby El Cerrito.

“It’s pretty special,” Semien said. “He was my dad’s favorite player growing up. It’s pretty cool to be in any conversation with him.”

The home run, which came on a 3-0 fastball from Sparkman that was blasted 105.6 mph off the bat and traveled a Statcast-estimated 415 feet, was part of a 3-for-5 day for Semien. While players might often get a bit fatigued at this point in the year, Semien only appears to get stronger.

Leading the AL with 151 games played, Semien is now 14-for-32 with five home runs and 10 RBIs over his last seven games.

“We talk about it every day. He’s been fantastic,” Melvin said. “Durable, power, average, on-base, defense -- he’s one of the better players in the league.”