CHICAGO - The challenge to Felix Hernandez this spring was that he move from perpetual phenomenon-hood to staff ace - embracing everything that term meant.

What it meant on Tuesday for the Seattle Mariners was following a tough loss in the first game of a double header by pitching even better than teammate Chris Jakubauskas had in losing to the Chicago White Sox, 2-1.

Felix was up to it.

Off to the first 4-0 start of his career, Hernandez went eight shutout innings - running his personal streak of scoreless innings to a career-best 19 - and beat Chicago, 9-1.

He had help. Limited to four hits and a run in the first game - when Jakubauskas allowed only two hits and lost - the Mariners exploded for 19 hits in the second, in including a career-high five by first baseman Russell Branyan.

All those hits and runs made it easier, but the bottom line for Hernandez is that he rose to the challenge and put up zeroes, something he's getting accustomed to.

"Felix stepped up with a performance we needed," manager Don Wakamatsu said. "But he's been stepping up all month."

Five starts into 2009, Hernandez has beaten Minnesota, Detroit, Tampa Bay and Chicago, going 4-0 with a 2.38 earned run average, and working 34 innings. In them, he's struck out 36 batters, nine of them Tuesday.

And, in large part because of their pitching, the Mariners are 13-8 and have served notice. To beat them, bring your best game.

"We've got pitching, we play good defense and we've gotten timely hitting,' Branyan said. "We're a good team playing well. We lost a tough one that first game, and we came out with a little fire for the second."

The White Sox won the opener when Bartolo Colon and two relievers stymied the Mariners on four hits, even as Jakubauskas was holding Chicago to a single and a double in the first complete game of is career.

That left the nightcap to Hernandez, the man Wakamatsu sought out early in spring training.

"He's been the young phenom for years," Wakamatsu said. "Now, it's time to step up and be the staff leader, the way Pedro Martinez did. That's Felix's challenge."

Going 4-0 in April is not quite Pedro-esque, but this is. Each of his last three wins came after a Seattle loss - and the other came on opening day.

When the Mariners opened the nightcap by scoring a first-inning run before he took the mound, Hernandez pitched like it was the only one he needed, and it might have been.

Inning after inning, he kept Chicago off the scoreboard and after eight innings, Hernandez was told he was done.

"I said 'no,' the first time they told me," Hernandez said. "The second time, I listened. I'm workin on that. It's like when we had four runs after the third inning, I told the guys in the dugout 'Save them! That's enough!'

"Any pitcher will tell you he likes run support."

When Ichiro opened the nightcap with a single, Wakamatsu went small ball and had Endy Chavez bunt Ichiro to second base. Green-lighted, Ichiro stole third - and Mike Sweeney singled him home.

"Any time you can get a lead to Felix, you do it," Wakamatsu said. "We did some little things really well tonight. We moved the runner over, we got him in." And taking Felix out after eight innings of shutout ball?

"We want as many starts from him as we can get this year," Wakamatsu said. "He'd gone 100 pitches, eight innings, on a cold night. It was enough."

All the runs Jakubauskas didn't get in the first game, the mariners scored in the nightcap. Branyan, who'd had 22 three-hit games in his career, had never had more.

"I guess I broke right through that four-hit barrier," he said.

Yuniesky Betancourt had four hits, including a three-run home run in the third inning, and a career-high five RBI. As a team, the Mariners were 10 for 20 with runners in scoring position. The White Sox? They went 1 for 5.

Anyone looking for explanations to Seattle's first-place record could have stopped with Tuesday's games. Starting pitchers Jakubauskas and Hernandez ate up 16 of the 17 innings pitched - and allowed a total of six hits in those 16 innings.

Asked about his streak of scoreless innings, Hernandez shushed the questioner.

"I just want to win games," he said. "I don't want to talk about a streak."

The double header may have helped explain a new attitude on this team, one that wasn't in plain sight a year ago, when it lost 101 games.

"We lost a tough game, we came right back and won the second game," Sweeney said. "We expect that of ourselves. That's what good teams do."