Guthrie thinks he arrived finally feeling normal after battling a strength-sapping virus.
"I think it is very important to our ballclub that he pitches well for us to win games in the second half," Trembley said. "We need quality starts out of him, and he is capable of reeling them off. He is capable of doing that, I have seen that before."
Not having pitched since leaving his July 7 start in the third inning due to a mysterious viral infection that attacked his muscles and left him completely fatigued for more than a week, Guthrie returned invigorated.
In arguably his best start of 2009, Guthrie allowed just three hits - including solo home runs to DeWayne Wise and Chris Getz - in eight innings, tying his longest outing of the year. He struck out five, walked one and had a three-ball count on only four of the 27 batters he faced.
"I felt really good the last two throwing sessions so I was very confident that I'd be able to go out there and work down in the zone and give us a chance to win," said Guthrie (7-8), who lowered his ERA from 5.35 to 5.12. "It's a nice start for the second half of the season."
Guthrie joked that if he looked different to Trembley this week it was because Guthrie's body fought the virus that had dogged him.
"He saw a lower blood enzyme level, that's what he probably saw," Guthrie said. "If that translates into a more focused and determined Jeremy, then it is. But I am not any more determined to pitch well than I was three or five days ago."
With the win, the Orioles (41-50) avoided a sweep to start the second half, improving to 15-29 on the road and 3-11 in road series finales. They also won for the fifth time in 15 Sundays this year, guaranteeing a better Sunday record than their 4-21 in 2008.
The Orioles won Sunday with an assist from the White Sox pitching staff and starter Jose Contreras (4-8), who allowed five runs (four earned) on five hits and four walks in 4 1/3 innings. He hit two batters and threw two wild pitches, which plated the Orioles' first two runs.
Orioles leadoff hitter Brian Roberts set the tone in the first by singling off Contreras' first pitch of the game. He then stole second, advanced to third on an errant throw by catcher Ramon Castro and scored courtesy of Contreras' wild pitch.
Roberts had the first of the Orioles' three stolen bases - tying a season high - and one of several strong base-running plays by a team hampered by base-path blunders. Their best moment came in the five-run fifth, with Gregg Zaun on first and one out.
Cesar Izturis hit a grounder to second baseman Chris Getz who should have turned and quickly thrown to second to start a potential inning-ending double play.
But the veteran Zaun started toward Getz and halted, distracting Getz before he threw to first for the sure out. First baseman Paul Konerko then threw to second for the tag out of Zaun, but Luke Scott had already scored the Orioles' sixth run.
"It's one of the things that they teach you young, you don't run into double plays like that," Zaun said. "I was happy with the base running, but it was a fundamental play."
With a new half, is it possible the Orioles will have a better sense on the base paths?
"Make sure everybody knows that there were three stolen bases today, the base running by Roberts, the base running by Zaun, let's give credit when credit is due," Trembley said. "When the positive occurs let's give credit to them. That was a really key play in the game [by Zaun]."
Zaun had arguably his best day as an Oriole, with three hits and four RBIs, the ninth time he has accomplished that in his career but his first as an Oriole since July 21, 1995.
Zaun hit his fourth homer of the season, a three-run shot in the ninth against Tony Pena, and he had the lone RBI hit in the fifth, an inning set up by three walks - two with the bases loaded - and a hit batsman.
Guthrie didn't need any more support, never facing more than four batters in an inning and never allowing more than one runner on base at a time. Before the game, he said he joked with Jason Berken that he was going to pitch a no-hitter.
He fell short of that goal, but he started the second half splendidly.
"I was unable to even throw a baseball [hard] on the second day before the all-star break began. I needed a break physically for that reason, and if it serves as a mental break as well, then that's another positive."