Then, he delivered.
Semien hit a tiebreaking RBI double in a two-run 12th, Jose Quintana pitched one-hit ball over seven innings, and the White Sox beat the Cubs 3-1 at Wrigley Field on Monday night.
"Sometimes you get a little bit more amped up," Semien said. "But the calmer I am, the better I do, usually."
Quintana and five relievers combined on a four-hitter, and the White Sox came away with the win after dropping four straight and six of seven to their crosstown rivals.
The Cubs lost even though Jeff Samardzija pitched three-hit ball over nine innings. He remained winless despite coming up big on the mound and delivering at the plate, coming through with the lone hit off Quintana and scoring the Cubs' lone run.
"You couldn't ask for anything more from a starting pitcher than what he gave us," manager Rick Renteria said. "So it's a shame that we weren't able to get (the win) for him."
The winning rally started when Alexei Ramirez singled off Justin Grimm with two out and stole second. Tyler Flowers walked, and Semien lined a 1-1 pitch over third baseman Mike Olt's head to make it 2-1.
In the bottom half, Matt Lindstrom walked Welington Castillo leading off before Nate Schierholtz bounced into a double play. He then gave up a single to Olt and struck out Luis Valbuena for his fifth save in eight chances.
Daniel Webb (3-0) struck out the lone batter he faced for the win.
Both teams got dominant starts, with Samardzija and Quintana each allowing one run on a chilly night with the wind blowing in.
The only hit off Quintana was a leadoff double in the sixth by Samardzija, who scored on a sacrifice fly by Junior Lake that tied it at 1.
In the bottom half, the Cubs' Anthony Rizzo singled off Ronald Belisario with one out and moved to second on a grounder to shortstop by Starlin Castro, with the throw from Alexei Ramirez deep in the hole barely beating him. The call was upheld after a replay review, and Castillo then struck out to send the game to extra innings.
The Cubs left two on in the 11th when Webb came in for Scott Downs and struck out Castro for the third out.
It was another hard-luck night for Samardzija, who struck out seven and walked two while throwing a career-high 126 pitches. He is 0-3 in seven starts this season despite a 1.62 ERA, and the Cubs are 1-6 when he pitches.
His most recent win was against San Diego on Aug. 24. In 13 starts since then, he's 0-5.
"We come out to win games every day regardless of who's on the mound or what the lineup is or who we're facing," he said. "You come out to win the game. Anytime you don't win, it's frustrating."
Quintana, meanwhile, retired the first 14 batters before walking Schierholtz and Olt.
Still, he took yet another no-decision. He has four after setting an American League record with 17 last season.
"He was great," manager Robin Ventura said. "Both pitchers were great. Q had a little extra life on it today. Would have liked to have kept him in there. He's not quite the hitter the other guy is. He pitched great for us. He was rolling there pretty good."
White Sox ace Chris Sale said he felt fine after throwing his first bullpen session since injuring his left arm. Sale threw 40 pitches before Monday's game. General manager Rick Hahn said the left-hander will go on a rehab assignment in the "coming couple weeks." ... Hahn also said reliever Nate Jones had back surgery and will be re-evaluated in a month. He is on the 60-day disabled list. ... RHP Edwin Jackson (2-2, 5.24 ERA) starts Tuesday for the Cubs, with RHP Hector Noesi (0-2, 11.12) pitching for the White Sox.