PITTSBURGH -- Pittsburgh Pirates second baseman Neil Walker understands not everybody is going to be a fan of Major League Baseball's expanded replay system, which threatens to slow down a sport that already struggles to be played with any sort of urgency.
Funny, there weren't many critics to be found on Monday at PNC Park.
The Pittsburgh native turned on a Villanueva changeup and sent it sailing over the Clemente Wall in right field for the first walk-off of his career and the first by the Pirates on opening day since Bob Bailey homered off San Francisco's Juan Marichal in a 1-0, 10-inning victory in 1965.
''This one feels pretty special,'' Walker said. ''This is a special day for this team, this organization. We've come a long way.''
So has the game.
After spending decades fighting the advances of technology, Major League Baseball has embraced the concept. Many calls can be challenged this season under an expanded system, and both teams wasted little time putting umpires to work.
The Cubs made history by initiating the first review under the new guidelines. Chicago manager Rick Renteria challenged a double-play call in the top of the fifth following a demonstrative ''safe'' call by Jeff Samardzija following a poorly executed sacrifice bunt attempt. First base umpire Bob Davidson's decision was confirmed on replay.
''It was a combination of Samardzjia's reaction and what we were looking at,'' Renteria said. ''We're still trying to figure out what clear and compelling evidence is. It's a work in progress.''
Chicago's luck with replay didn't get any better later.
A safe call on a pickoff attempt by Bryan Morris (1-0) with one out in the top of the 10th was reversed after Pirates manager Clint Hurdle requested a replay, sending Chicago's Emilio Bonifacio back to the dugout after a delay of 2 1/2 minutes.
''Most of the time on pickoffs, it's got to be very noticeable for the umpire,'' Morris said. ''Those bang-bang plays are always going to go to the runner. I guess that's why it's good to have replay.''
The largest regular season crowd in PNC Park's 14-season history (39,833) roared its approval. The din only grew louder when Walker's drive to right field finished halfway up the seats. That capped a giddy day for a team freed from two decades of losing after a breakout 2013 in which it won 94 games and made the playoffs for the first time since 1992.
Former Pittsburgh star Barry Bonds presented centerfielder Andrew McCutchen with the NL MVP award that McCutchen earned last year. Bonds received mixed reviews, though the vitriol that accompanied his late career visits to Pittsburgh while playing for San Francisco was noticeably absent.
Bonifacio went 4 for 5 for Chicago, but the Cubs were 0 for 11 with runners in scoring position and wasted a fine start by Samardzija, who scattered five hits over seven innings.
''I was happy with the way I kept the ball down in the strike zone,'' Samardzija said. ''It helped to get the double plays because they made the overall outing look a little better than it really was.''
Travis Ishikawa had two of the six hits by Pittsburgh.
Starter Francisco Liriano tied a team record shared by three other pitchers for most strikeouts on opening day by fanning 10 in six innings. While he struggled with his command -- needing 104 pitches to get 18 outs -- he was sharp when he needed to be and Pittsburgh's bullpen did the rest.
Pirates C Chris Stewart took batting practice and says he is coming along ahead of schedule in his rehab from knee surgery. Stewart believes he can beat the timetable of late April for his return. ... Chicago OF Brian Bogusevic was unavailable because of ankle soreness. He is expected to be ready to play Wednesday. ... The teams are off Tuesday. Chicago's Edwin Jackson faces Pittsburgh's Charlie Morton on Wednesday night.