CHICAGO -- Javier Báez ran through first base, turned around and saw his teammates pouring out of the Cubs' dugout on Sunday. In previous years, it was a moment that would have soon included a celebratory mob scene at Wrigley Field.

Báez had just lined a walk-off single to center to deliver a 2-1 victory over the Pirates in the 11th inning. It was the Cubs' first taste of the new extra-inning rules for 2020, and also the team's first experience of navigating an on-field party while practicing safety in the COVID-19 era.

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"I wanted to bring out the masks and just everyone jump on him," Cubs left fielder Kyle Schwarber quipped. "Everyone wanted to dogpile Javy, but then we were like, 'You know what? Let's keep it down a little bit. Let's be cool. Be sure that we're being responsible.'"

Báez ran to the mound, where a group of teammates circled around the shortstop and began jumping up and down with their hands in the air. From the third-base dugout, Cubs manager David Ross got a kick out of the unusual scene.

"It definitely made me smile and laugh in the moment," said Ross, whose club completed a three-game sweep to improve to 7-2 on the season. "Javy in the middle of everybody kind of jumping around. That was fun to see."

These were three keys to the Cubs' extra-inning win:

1. The bullpen
Cubs lefty Jon Lester gave his team six impressive innings before bowing out of a 1-1 ballgame. After his performance, he watched right-handers Casey Sadler and Dan Winkler log three combined innings before the 2020 extra-inning rules came into play.

"I can only imagine what that feels like," said Lester, referring to an automatic runner being placed on second base at the outset of each extra frame. "You haven't even thrown a pitch yet and you've got a guy on second base. A lot of high-intensity work.

For the 10th and 11th innings -- after rain delayed the game for 1 hour and 4 minutes in the bottom of the ninth -- Ross handed the ball to Ryan Tepera and Jeremy Jeffress, respectively. Tepera faced the minimum with the help of a crucial defensive play behind him (more on that in a moment), and Jeffress went three up, three down to set up the decisive push.

"Two veteran guys," Ross said. "We've talked about that -- the poise in the moment."

2. The defense
The Pirates placed catcher Jacob Stallings at second base to start the 10th and pinch-hitter Josh Bell immediately sliced a pitch from Tepera into left field. Schwarber gloved the ball, glanced at Pittsburgh third-base coach Joey Cora and came up firing to the plate.

"He's giving the sign to go. It was kind of just, get it and let it go," Schwarber said. "I was just praying that it was on line."

Cubs catcher Willson Contreras collected the throw, turned to his left, braced himself and collided with Stallings. Contreras held onto the ball for the out and gave a quick pat on Stallings' back to let him know there were no hard feelings about the bang-bang play. A review revealed there was no violation of the home-plate collision rule.

"That's old school baseball right there," Schwarber said. " I don't think anyone's afraid to see that. Good, clean play all around."

In the 11th inning, José Osuna sent a sharp grounder to Báez, who swiftly turned and relayed the ball to Cubs third baseman David Bote. Kevin Newman -- the automatic runner -- was tagged out easily for an important inning-opening out.

"Javy, that's communication," Bote said. "That's constant contact with each other, knowing where people are, saying, 'Hey, Javy, on a one-hopper and he breaks, I've got you on a throw.' You get to the point where you understand it with just a look."

3. The winning rally
Ross said he felt the Cubs' first experience in extras exposed some flaws in need of work, but the manager did appreciate that the new rules force an offense into strategy mode.

"You're not having everybody trying to hit homers," Ross said. "I think sometimes in extra innings it ends up being a home run derby. These guys, you feel that sense of having good at-bats -- things that we preach -- and moving the baseball and getting runners over. All the little details that matter in winning."

In the 10th, the Cubs drew the third baseman (Osuna) in when Nico Hoerner squared to bunt, and automatic runner Steven Souza Jr. stole third base. Chicago could not cash in with a pair of runners in scoring position and one out. Albert Almora Jr. struck out with a five-man infield employed and Bote popped out.

Bote took over as the automatic runner in the 11th and sprinted to third on a deep flyout to right by Anthony Rizzo, who clapped his hands hard as he jogged off the field. That set things up for Báez, who sent a 2-0 slider from Cody Ponce up the middle for the win.

"It's definitely interesting," Schwarber said. "I think strategy has a big part in the game there. I think you're going to see different beliefs throughout the league. ... But I think we handled it very well."

That includes the walk-off celebration.