ST. PETERSBURG, Fla. -- As a youngster, J.P. Howell dreamed of someday developing into a dominating pitcher like Randy Johnson.
"He was the man growing up as a lefty," the Tampa Bay Devil Rays prospect said Saturday night after beating the Big Unit and the New York Yankees 8-0. "With him you don't have much room (for error). ... But you try not to think much about who you're going against."
Ty Wigginton and B.J. Upton homered, spoiling Johnson's bid to become the American League's third 18-game winner.
Howell (1-3) allowed three hits in seven innings, and relievers Dan Miceli and Juan Salas finished Tampa Bay's first shutout of the Yankees since Tanyon Sturtze beat Roger Clemens 4-0 on Sept. 25, 2001.
Johnson lost for the first time in a month, but hasn't pitched well in his past three starts.
"I got my work in, I guess," said Johnson, who has allowed 15 runs and 24 hits over his last 17 2/3 innings against Baltimore, Boston and Tampa Bay.
"Things haven't been where I want them to be my last three starts. I'm pretty much aware of that. Going into my last start (of the regular season), things need to be a lot better."
Howell got his first major league victory since last Sept. 26, when he pitched five innings for Kansas City in a combined 5-0 shutout at Minnesota. The Devil Rays obtained him from the Royals in a trade that sent outfielder Joey Gathright to Kansas City in June.
Saturday night's win was the 23-year-old's first in four starts since being promoted from Triple-A Durham on Aug. 25. It's also the first game a Devil Rays starter has won since Aug. 21.
"I think I was just in control of myself a little more," Howell said. "I've been asking questions trying to learn and it showed tonight."
Rocco Baldelli doubled to drive in two runs against Johnson (17-11) in the third, and Wigginton hit his 22nd homer for a 3-0 lead in the fourth. Upton's two-run shot in the sixth was his first in 42 games since being recalled from Triple-A Durham.
Wigginton, who was 3-for-4 with three RBI, added a two-run single off Jose Veras in the seventh.
In failing to join teammate Chien-Ming Wang and Minnesota's Johan Santana as the only 18-game winners in the majors, Johnson allowed five runs and seven hits in six innings. He walked one and struck out seven.
Manager Joe Torre said he's not alarmed by Johnson's performance of late.
"I think we're too close to the finish line to be concerned about it," Torre said. "As long as he's healthy we'll look to the postseason, and obviously the postseason usually brings out something a little bit different in players and pitchers both."
Howell allowed singles to Robinson Cano in the second and Derek Jeter in the fourth, as well as a double to Hideki Matsui in the seventh. The left-hander walked two and struck out three before being replaced by Miceli at the start of the eighth.
Salas pitched the ninth for Tampa Bay to finish the four-hitter, the fourth time the Yankees have been shut out this season.
The Devil Rays won for just the fourth times in 16 games against the Yankees this year. Amazingly, the last-place team is 40-39 at home but 37 games under .500 on the road (19-56), including a 2-28 mark since July 1.
Johnson, who won six of his previous seven decisions, lost for the first time since Seattle beat him 4-2 on Aug. 23. In three starts against the Devil Rays this season, he's 1-2 and has allowed 16 earned runs in 16 innings.
Howell allowed one runner past second base and worked out of potentially troublesome spots in the second and sixth.
Gary Sheffield, making his second start at first base for the Yankees, walked and moved to third on Cano's single with one out in the second. Howell escaped when Matsui hit a checked-swing, soft liner back to the pitcher, who then threw to first base to double off Cano.
Bobby Abreu walked and Alex Rodriguez was hit by a pitch with two outs in the sixth. Sheffield, hitless in five at-bats since spending more than three months on the disabled list with a wrist injury, flied out to end the threat.
Wigginton has three homers in 25 career at-bats against Johnson. ... Yankees CF Johnny Damon sat out for the third straight game since cutting his throwing hand making a diving catch in Toronto on Tuesday. He could return to the lineup on Sunday. ... After an impressive debut at first base Friday night, Sheffield committed his first error at his new position when he dropped Johnson's throw to first base on Ben Zobrist's fifth-inning bunt. ... The Yankees were blanked for the first time since losing 5-0 at Kansas City on Sept. 5.