The Kansas City Royals are going through the growing pains of a promising young team.

Jeff Niemann won his sixth consecutive decision, Ben Zobrist had a two-run triple and the Tampa Bay Rays completed a four-game sweep with a 4-1 victory over the Royals on Thursday.

"It's miserable when you lose," Kansas City manager Ned Yost said. "But you have to remind yourself everyday where you're headed, knowing that is all part of the process. There's no way to make it quicker. You have to go through it."

Kansas City, which has the youngest 25-man roster in the majors, has lost six of seven. The Royals had 11 hits, but went 1 for 9 with runners in scoring position and left 10 on base.

"This is the most painful part," Yost said. "This is where it hurts. We start to really show some improvement, but you can't get over the hump in winning games. You're really close. The hardest part is maintaining your patience and maintaining your sense of reality. Exactly what you're trying to accomplish and how you're going to get there."

Niemann (7-4) allowed one run and nine hits over 6 1-3 innings. The right-hander is 6-0 in nine starts since returning from a strained lower back.

The Rays first four-game home sweep since July 28-31, 2005 — also against Kansas City — included an 8-7 win Wednesday night in which Tampa Bay scored five times in the ninth.

Kansas City rookie left-hander Danny Duffy (3-6) gave up three runs and five hits over seven innings.

"I feel like I gave it my all," Duffy said. "I had a solid outing, but it wasn't enough."

After Joel Peralta threw 1 2-3 scoreless innings for Tampa Bay, Kyle Farnsworth pitched the ninth for his 21st save.

Tampa Bay took a 2-1 lead when Zobrist drove in two runs on a third-inning triple. Desmond Jennings tripled and scored to make it 3-1 on Evan Longoria's fifth-inning sacrifice fly.

Sean Rodriguez extended the advantage to 4-1 on an eighth-inning RBI single.

The Royals had runners on second and third with no outs in the first, but scored just one run on Eric Hosmer's grounder. Kansas City was hitless in five at-bats with runners in scoring position through two innings.

Hosmer was retired on a grounder with two on and two outs in the fifth. Niemann struck out Alex Gordon with two outs and the bases loaded one inning later.

"You see all the young talent here," Kansas City right fielder Jeff Francoeur said. "Now it's learning how to play in the big leagues. Every single person goes through it. Hopefully guys can learn how to do things the rest of this year."

Niemann retired 10 in a row after Alcides Escobar had an infield single with one out in the second. He is 4-0 in six games, including five starts, against Kansas City.

Rays designated hitter Johnny Damon singled during the first and moved past George Davis into 65th place on the all-time hits list with 2,684.

Notes: Yost did not talk with his team about Wednesday's tough loss. "They're resilient," he said. "They're fine." ... Royals LHP Bruce Chen (6-5) will go against Chicago White Sox RHP Zach Stewart (1-0) on Friday night. Chen is 1-3 with a 3.66 ERA in 12 games, including seven starts, against the White Sox. ... Royals CF Melky Cabrera had three hits in his 49th multihit game of the season. ... Royals rookie C Salvador Perez had two singles in four at-bats in his second game since joining the team from Triple-Omaha. ... Duffy has allowed three earned runs or less in five of his last six outings.