MILWAUKEE (AP) -- Todd Helton's 16th straight opening day start for the Colorado Rockies could be his last.
The five-time All-Star first baseman turns 40 in August and is entering the final season of his contract.
''I do realize it's coming to an end and enjoy everything a bit more,'' he said ahead of Monday's game at Milwaukee. ''Sit back and just be in the moment a little bit more.''
Helton hit .238 in 69 games last year, both career lows.
''Everything surrounding opening day, they're all special,'' said Helton, whose season ended in August because of a hip injury that required surgery. ''It's just a great time of year knowing you're going to be playing baseball again, baseball's here.''
Walt Weiss replaced Jim Tracy in Colorado's dugout, and the 1988 AL Rookie of the Year is making the rare leap from high school coach to major league manager. Prior to this job, Weiss' only head coaching job was at Regis Jesuit High School in Aurora, Colo., where he led his son's team to a 20-6 record and a spot in the state semifinals last spring.
Weiss took over a team that finished a franchise-worst 64-98 and last in the NL West, 30 games behind the division and World Series champion San Francisco Giants.
''There is no question the pink elephant in the room is I haven't done this before,'' Weiss said when he was hired. ''This is a job that I'm going to have to figure out on the fly.''
Colorado's Jhoulys Chacin takes the mound for his first opening day start and perhaps will end the Rockies' streak of 102 games since June 12 without a starter reaching 100 pitches. That's easily the longest in the majors since such records started in 1988, according to STATS.
''Chacin is a guy who can pitch,'' Weiss said. ''He's got a great changeup, a good slider. He's had very good success at the major league level. He's just got to command his stuff. When he does, he can go through big league lineups.''
Yovani Gallardo makes his fourth opening day start for the Brewers, who begin the season against Colorado for the second time in four years. The Rockies won their 2010 opener at Miller Park.
''Gallardo's our No. 1 guy,'' catcher Jonathan Lucroy said. ''He's our opening day guy for a reason. He sets the tone for the rest of the pitching staff to follow.''
Milwaukee's rotation got a boost last week when Kyle Lohse agreed to a $33 million, three-year contract. Lohse was 16-3 with a 2.86 ERA for St. Louis last season, pitching a career-high 211 innings.
''Yo has the experience and he has the mindset to be a leader on the pitching staff,'' Lucroy said. ''With Kyle Lohse here now, they can mentor a lot of the other guys.''
Gallardo is 0-2 in opening day starts.
''Yo's becoming a vocal leader,'' Milwaukee manager Ron Roenicke said. ''Guys are going to look to him to see what kind of workload they need to do. They are going to look at him to see how he gets along when he struggles a little bit. So, there's a lot of examples that Yo's going to show these young guys on how to go about it.''
After reaching the 2011 NL championship series in Roenicke's first season, Milwaukee was third in the NL Central last year at 83-79, 14 games behind the division champion Cincinnati Reds. The Brewers have eight players who are on an opening day big roster for the first time, including pitchers Wily Peralta, Mike Fiers, Jim Henderson and Alfredo Figaro.
''We've got a great group of young guys,'' Peralta said. ''We don't have too much experience, but I think we've got great arms.''
Alex Gonzalez, back from season-ending knee surgery, makes his first big league appearance at first base after Mat Gamel blew out his surgically repaired knee early in spring training. Regular first baseman Corey Hart is due back in May from knee surgery.
Ryan Braun, the Brewers' top slugger, again faces questions about performance-enhancing drugs. Before spring training last season, the 2011 NL MVP won his appeal of a positive drug test during the 2011 postseason, succeeding with his argument about a chain-of-custody that didn't adhere to the procedures in force at the time.
This year. MLB is investigating the appearance of the left fielder's name on documents purportedly from a closed anti-aging clinic in Florida that was accused in media accounts of distributing banned performance-enhancing drugs. Braun issued a statement saying he had used the clinic's operator, Anthony Bosch, as a consultant during his appeal of his 2011 positive test.
Rookie outfielder Khris Davis made the Brewers after batting .262 in spring training with six homers and a team-high 16 RBIs.
AP Sports Writer Lynn DeBruin in Salt Lake City contributed to this report.