The Replacements and Dinosaur Jr. – two influential indie-rock bands at very different points in their post-reunion lives – teamed up to give some lucky Boston fans a big treat with a free show at the 800-person club the Sinclair on April 27.

After local openers the Young Leaves made good use of a once-in-a-lifetime opportunity to open for two of their heroes, Dinosaur Jr. took the stage for a mesmerizing nine-song set that pulled tracks from eight of their 10 studio albums and still found time for their great cover of the Cure's "Just Like Heaven."

The inclusion of a track from each of the three fantastic records (2007's Beyond, 2009's Farm and 2012's I Bet on Sky) that the group has released since their surprising reformation over a decade ago proved once again just how vital and rewarding this reunion has been. And, as my good buddy Jed from the Boston Herald points out, there's at least an 11 percent chance that J. Mascis is actually your favorite guitar player.

That was a heck of a lot for the two remaining original Replacements, Paul Westerberg and Tommy Stinson, to live up to. After all, they're not even three years into their reunion, and, apart from a highly experimental free-jazz track posted to the internet for free and the bluesy, gently mocking live-only "Whole Food Blues," have yet to share any new music with the world.

So while a new Replacements album remains a possibility, this tour could also easily end up simply as a well-deserved, long-delayed victory lap or retirement fund booster campaign. And judging from the rabid fan reaction to their 24-song set (and the fact that I could have traded my ticket for a Land Rover or a new apartment in Harvard Square), it would seem they could ride that nostalgia train for quite some time.

Obviously, some of the chaos and wildness of the group's earlier days has been traded for a more evenly-paced professionalism. Only an idiot would ask them to make (or feign) a return to their former drunken and ultimately self-destructive concert antics, and nobody in the crowd seemed anything less that fully satisfied as the band reverently delivered classic song after classic song (for example, check out "Alex Chilton" from the gig in the video above).

Time will tell if Westerberg and Stinson are able to add to their recorded legacy and build a true second chapter as well as Dinosaur Jr. have, but there sure were a lot of people in the crowd on this night that can't (hardly) wait to see them try.