Boston ? Bill Mueller put Jaime Cerda’s first pitch over the Green Monster — foul — missing a game-tying grand slam by a few feet.

Mueller then fouled off eight more pitches in a 13-pitch at-bat, including another shot that would have needed some Carlton Fisk-style body English to stay fair.

With a full count, two outs and the bases loaded, Cerda then got Mueller to ground out to third base to squelch Boston’s biggest threat and secure Kansas City’s 8-4 victory over the Red Sox on Sunday.

After the first pitch, “I turned and looked and thought, ‘Wow, that wall in left field is pretty close,” said Cerda, who never had been to Fenway Park before. “The electricity out there was unbelievable. Nine pitches in a row, and the crowd is getting louder and louder and louder. It was real fun, I’ll tell you that.”

Darrell May earned his first victory of the season, and Carlos Beltran drove in four runs on three hits to help the Royals snap a four-game losing streak. May (1-3) allowed two runs on seven hits and a walk, striking out five before leaving with the bases loaded and two outs in the sixth.

Cerda came in to face Mueller, who hit a two-run homer in the second inning and was batting 5-for-10 with four homers and seven RBIs in his career against May. After the first shot went foul, Mueller took two balls before fouling off eight consecutive pitches.

The next pitch was high to make it a full count, and then Mueller hit an easy bouncer to third to end the threat.

“You beat yourself up every time you make an out,” Mueller said.

But his boss appreciated the effort.

“What an at-bat,” Red Sox manager Terry Francona said. “And, you know, the more pitches he saw the better he felt. Just couldn’t keep one of those balls fair. It was a great at-bat. A very professional at-bat.”

Cerda went two innings and allowed one run on one hit — Manny Ramirez’s solo homer in the eighth. Mike Sweeney was 2-for-2 with three intentional walks and Kelly Stinnett homered for the Royals, who won on the road for just the third time all season.

“When a ballclub’s struggling, to win a ballgame can mean a lot,” manager Tony Pena said. “It might turn around something. It’s time.”

Derek Lowe (3-3) gave up six runs on five hits and five walks in 5 2-3 innings and Boston lost for the first time in five games. He gave up two unearned runs in the third and ran into more trouble after bringing a 2-2 tie into the sixth.

Joe Randa led off with a single and, two outs later, Desi Relaford and David DeJesus walked. Mueller fielded Angel Berroa’s grounder at third but his throw to second was not in time for the force, allowing the tiebreaking run to score.

With Mark Malaska pitching, Beltran doubled to clear the bases and make it 6-2.

The Red Sox had a chance to tie it in the bottom of the sixth, when they loaded the bases but came away empty-handed.

David Ortiz doubled with one out and Ramirez walked. Jason Varitek struck out looking before Kevin Millar reached on an infield single to load the bases.

Beltran doubled in another run in the eighth to make it 7-2, then Ramirez homered. Pokey Reese walked and scored on Johnny Damon’s broken-bat single with two outs in the ninth to make it 8-4 before Dennys Reyes relieved Scott Sullivan and got Mark Bellhorn for the final out.

The Red Sox took a 2-0 lead in the second when Millar singled and Mueller lined one over the Green Monster, but Kansas City tied it in the third.

Relaford walked and DeJesus hit a grounder to first baseman David McCarty, who tried to get the lead runner. Shortstop Reese came off the bag before he took the throw and was charged with an error. Berroa struck out and Beltran grounded out to first to advance the runners before Sweeney doubled to make it 2-2.

Notes: May’s last victory was Sept. 21, 2003, a 10-4 victory over the White Sox. … It was the 14th sellout of the season and 78th in a row for the Red Sox. … The Red Sox have allowed 19 unearned runs as a team, nine of them when Lowe is pitching. … The start of the game was delayed 16 minutes because of rain. … Ramirez has 119 homers since coming to Boston, tying him with Joe Cronin for 20th on the team’s all-time list. … Stinnett came in to replace Benito Santiago, who was thrown out for arguing a called third strike to end the seventh.