Messi ended a goal drought of three matches with his 13th career hat-trick to take his tally to 19 goals this campaign when Barcelona beat Mallorca 5-0 on Saturday to extend their unbeaten run to 16 games in all competitions.
The European champions are tied at the top of Group H with AC Milan, who can also advance tonight if they beat BATE Borisov of Belarus away.
Messi also hit the post twice on Saturday and with Plzen needing to go for the win, he has a good chance of exploiting the home side to score what would be his 200th goal for the club.
"We know Messi is the world's best player, that he's the leader of this team and a player who changes a game," Sergio Busquets, the Barcelona midfielder said. "But he's not a machine and there are games when he won't score goals."
Coming off 4-1 and 5-0 league victories since losing at Barcelona last time out, Plzen are upbeat.
"When you score, it boosts confidence," Milan Petrzela, the midfielder, said. "I hope we could be better than in the previous game. Barcelona come to win, that's for sure. They play a game of their own and they don't care who they face."
Elsewhere, Chelsea have the chance for some respite from their domestic form when they travel to Genk, the Belgian champions, who are bottom of Group E.
Bayer Leverkusen face Valencia in the group's other game.
Saturday's 5-3 home defeat to London rivals Arsenal was Chelsea's second successive loss in the Premier League and a worst home defeat by Arsenal since 1934. Chelsea have not kept a clean sheet since the opening day of the season, but Andre Villas-Boas will not change the way his team plays.
"The philosophy is a personal value and a club value," the manager said. "It is something that makes us all proud and we will stick to this philosophy. It is our way of playing and we are proud of the way we play. We just have to correct things."