Soriano hit a leadoff home run and made a great throw to preserve a tie in the top of the eighth. The Cubs then scored a strange, go-ahead run in the bottom half of the inning after Ken Griffey Jr. was injured to beat the Cincinnati Reds 3-2.
The victory, coupled with Houston's 5-4 win over Milwaukee, gave the Cubs a one-game lead.
"If ever there was a must game for us this year, truthfully this was it," manager Lou Piniella said.
And Soriano provided the boost.
It was the 16th assist of the season for Soriano, a former second baseman.
"He hit it very hard and I took it on once bounce and made a good throw," Soriano said. "That's what I have to do. I know the runner on second runs very good."
Soriano's throw with a three-quarter motion is deceptive and arrives quickly.
"I'm happy that they run on me," he said.
"He's got that little fade into home plate. I wish I had that on the golf course," Piniella said.
With one out in the Cubs eighth, Ryan Theriot singled and made it second when Griffey fumbled the ball in right field for an error.
Derrek Lee followed with another single to right. As Griffey fielded the ball and started to make a throw, he stopped in pain. Griffey underhanded the ball back to the infield and fell to the ground as Theriot held third.
Griffey stayed down for several minutes and gingerly walked off with trainers at his side. The Reds said he had a lower abdominal strain.
"Hopefully it's not as bad as it feels," said Griffey, who will return to Cincinnati on Thursday to be examined by team medical director Dr. Timothy Kremchek.
Griffey said he got hurt when he made a little change of direction after backhanding Lee's hit and doesn't remember much about his underhanded throw.
"I knew I threw it, but that's about it," he said. "It's been a little sore for a while. But it's a situation where the games don't mean anything for us, but you have to go out there and try to finish strong and hopefully be tough on other teams."
Mike Stanton replaced Gary Majewski (0-3) and pinch-hitter Matt Murton hit a sinking liner to left that a sliding Adam Dunn was ruled to have trapped. Dunn threw to second to force Lee as Theriot scored.
"I have to look at the replay, but I know I caught it," Dunn said. "It wouldn't have mattered either way but that was kind of the reason that I slid that way instead of diving head first because at least I would have had a chance to maybe make a throw."
Dunn said the outfield at Wrigley Field is dangerous.
"I'm surprised more people don't get injured out there. It's as bad as there is," he said. "It's worse than playing in a parking lot. It looks like they had a monster truck rally. It's terrible. There's potholes. It's bad. It's unsafe."
Bob Howry (6-7) pitched two innings for the win.
Soriano's leadoff homer was his ninth the season, setting a Cubs' franchise record. Rick Monday hit eight in 1976.
Soto, the Pacific Coast League Player of the Year, hit his second homer since being recalled on Sept. 1.
Encarnacion hit his 15th, and second in two nights, to tie it at 1-1 in the second.
Dunn reached 40 homers for the fourth consecutive season -- a club record -- by launching a long drive onto Sheffield Avenue for a 2-1 lead in the fourth.
Like Carlos Zambrano on Tuesday night, Lilly worked on short rest so he could get two more starts in the final week and a half of the regular season. He gave up an infield hit to Hopper and a single to Jeff Keppinger to start the first, but escaped by getting Griffey to ground into a double play.
The Reds threatened again in the seventh when Dunn walked and Lee missed Joey Votto's grounder to first base for an error, putting runners at the corners. Lilly struck out David Ross and pinch-hitter Alex Gonzalez, leaving the game tied.
- Shearn spent 12 years in the minors before making his major league debut last month. He mixed an assortment of pitches at different speeds -- in one three-pitch sequence, his offerings were clocked at 86 mph, 68 and then 74.
- Mark DeRosa was 2-for-2 and is 14-for-15 in his last four games against the Reds.
- Dunn's homer was the 20th of his career at Wrigley Field.