BOSTON — An early lead against the best team in baseball went for naught, as the Royals lost 10-6 to the Boston Red Sox on Monday night.

The Royals' evening at Fenway Park began with promise. They took advantage of Red Sox starting pitcher Eduardo Rodriguez's erraticism in the first inning, forcing his pitch count up to 35 in the frame and drawing a pair of bases-loaded walks.

But Alex Gordon grounded into an inning-ending double play before they could continue any damage.

On a night that featured Xander Bogaerts hitting the Red Sox's sixth grand slam of the season, and Royals starting pitcher Jason Hammel surrendering eight earned runs in 4 2/3 innings, the double play was hardly the most egregious moment of the Royals' 21st loss.

But the moment represented a microcosm of the Royals' season: They entered Monday with four hits in bases-loaded situations. Jon Jay increased the total to five when he chopped a sharp ground ball to second baseman Eduardo Nunez that was ruled an infield hit. It scored the Royals' third run of the inning.

For a fleeting two innings, the Royals held onto their lead. Hammel shook off Mitch Moreland's leadoff home run in the second and retired the next five batters he faced.

But the Red Sox unraveled him in the third inning. With two outs, they strung together a pair of hits and drew back to back walks. Then Bogaerts drove the eighth pitch of his at-bat over the Green Monster in left field for a grand slam that gave the Red Sox a 6-3 lead.

The Royals attempted a rally in the fourth, with Alcides Escobar driving home Gordon on a double and Escobar immediately scoring on Whit Merrifield's two-base hit.

But the Red Sox scored four more runs over the remainder of the game, including twice against reliever Scott Barlow, who made his major-league debut.

Meanwhile, the Boston bullpen held the Royals to four hits after Rodriguez departed at the end of the fourth inning.

The Royals stranded seven men on base and dropped to 7-21, matching the Cincinnati Reds for the worst record in baseball.