John Danks will have a tough act to follow this afternoon when the Chicago White Sox go for a sweep in their three-game series with the Seattle Mariners at Safeco Field.

The White Sox have won the first two games of this set, but on Saturday they did so in historic fashion, as Philip Humber tossed the 21st perfect game in major league history, leading Chicago to a 4-0 win.

Humber struck out nine batters, including two in the ninth inning. The game ended when Brendan Ryan, on a 3-2 count, swung at a low and outside breaking ball that got past catcher A.J. Pierzynski.

Pierzynski scrambled to throw Ryan out at first base, and Humber's teammates piled on the right-hander in the infield.

"I don't know what to say," Humber said. "I don't know what Philip Humber is doing in this list (of perfect game throwers), I have no idea what my name is doing there, but I'm thankful it's there."

But the ending came with some controversy after it looked like Ryan may have checked his swing.

"I was shaking because you don't get the opportunity to be in that situation very often," Pierzynski said. "The way Phil was pitching and what it would mean to him, his family and his career, it's just amazing. I'm still in shock and so happy for Phil, I'm kind of speechless right now."

Blake Beavan (1-2) took the loss after giving up three runs on seven hits and one walk over six innings. The Mariners have dropped four of their last five games.

"It was just one of those freak days in baseball," Mariners infielder Chone Figgins said. "You come to the ballpark you never know what's going to happen."

Today, it will be Danks, who is 1-2 with a 4.82 ERA in three starts. Danks has alternated wins and losses to start the season and on Tuesday absorbed the loss against Baltimore, as he allowed three runs and five hits in seven innings.

"He battled," manager Robin Ventura said. "He just had two pitches he wants back. He gives you everything he's got and it's just one of those games."

He is 6-4 with a 2.72 ERA in 11 starts versus the Mariners. However, he's won his last five starts against them and matched a career-high with 10 strikeouts the last time he faced them.

Seattle, meanwhile, will counter with veteran righty-hander Kevin Millwood, who is still searching for his first win of 2012. Millwood has yet to receive a decision in either of his two starts, but is coming off a horrible outing on Tuesday against Cleveland, which battered him for six earned runs in only four innings of work.

"You try to figure out what's not right and try to fix it," Millwood said. "Tonight, I wasn't able to do that."

Millwood has struggled in his career against the White Sox, posting a 1-5 mark to go along with a 3.14 ERA in 11 starts.

Chicago has dominated the Mariners lately, winning 18 of the last 21 matchups, with nine of those wins coming at Safeco.