St. Petersburg, Fla. ? 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 61/3 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 victory 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 12/3 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.

Tampa Bay’s 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.