CHICAGO -- As the Washington Nationals' team bus sat in traffic en route to the hotel on Tuesday night, the club facing elimination heading into Game 4 of the National League Division Series against the Chicago Cubs on Wednesday, Stephen Strasburg didn't give himself much of a chance of taking an active role in keeping his team's season alive.

Physically drained by flu-like symptoms that set in last week, Strasburg believed he had little to offer. Despite still not feeling at full health when he woke up Wednesday morning, Strasburg arrived at Wrigley Field, walked into manager Dusty Baker's office and said he wanted the ball.

The right-hander made the most of the opportunity.

Strasburg threw seven scoreless innings and struck out 12, and Michael A. Taylor hit an eighth-inning grand slam to draw the Nationals even at two games apiece in the best-of-five series with a 5-0 victory over the Cubs.

The fifth and deciding game will be played Thursday in Washington. The winner advances to the NL Championship Series to face the Los Angeles Dodgers.

Strasburg, who held the Cubs without a hit for the first 5 2/3 innings in Game 1 of the series, is a major reason why the Nationals still have life. On Wednesday, he allowed just three hits and walked two while striking out the side three times.

"I'm surprised I was able to hang in there," Strasburg said. "I think it's just one of those situations where, you know, (you) try and break the game down, keep it simple and just know going in, whatever I have in the tank, I'm giving it everything I have."

With the Nationals clinging to a 1-0 lead in the eighth, Taylor blew the game open with the first postseason grand slam in franchise history off Wade Davis. The Cubs closer entered the game with two outs in the inning after reliever Carl Edwards Jr. walked a pair of hitters to load the bases.

Davis took over and surrendered the home run, which drifted into the basket in front of the right field bleachers.

"I was just kind of numb just running around the bases," Taylor said. "I didn't think it was going to get out the way the wind was blowing in."

Taylor's home run proved to be the finishing blow the Nationals needed after Strasburg (1-1), who admitted to not having a lot of energy, kept the Cubs off balance.

"I really stuck to one pitch at a time," he said. "Before I knew it, I was seven innings down."

The Nationals took a 1-0 lead with an unearned run in the third inning. After Trea Turner doubled off Cubs starter Jake Arrieta with one out and advanced to third on a wild pitch, Arrieta struck out Jayson Werth to get within an out of getting out of the inning.

Following a Bryce Harper walk, Cubs shortstop Addison Russell booted a Ryan Zimmerman ground ball, allowing Turner to score.

The Nationals loaded the bases in the fourth inning with Arrieta laboring. Arrieta (0-1) allowed an Anthony Rendon leadoff double and then issued walks to Taylor and Turner. However, Arrieta struck out Werth looking to wiggle out of trouble.

Arrieta allowed two hits and no earned runs over four innings. He walked five and struck out four.

Before the Nationals' four-run eighth inning, the Cubs had no answer for Strasburg, who was dominant with his changeup and kept the Cubs from ever being able to build any offensive momentum.

"We have to be better in the (strike zone)," said Cubs manager Joe Maddon, who called Strasburg "spectacular."

"We have to force their pitchers in the zone more consistently and not miss your pitch when you see it. It really comes down to that."

NOTES: Nationals SS Trea Turner snapped an 0-for-13 drought with a one-out double in the third inning. The hit was the first of the NLDS for the Washington leadoff hitter. ... Cubs manager Joe Maddon tweaked his lineup prior to Game 4 after the Nationals announced RHP Stephen Strasburg would start in place of RHP Tanner Roark. Cubs RF Jason Heyward was inserted in the No. 7 hole in place of OF Kyle Schwarber. ... Nationals manager Dusty Baker said Roark could be a candidate to pitch in Game 5 on Thursday. ... Cubs LHP Jon Lester entered the game in the fifth inning and made his first relief appearance since Game 7 of the 2016 World Series. He was charged with one run in 3 2/3 innings.