Messi cheered and lifted his good left arm in victory after his teammates showed more than enough class to convincingly beat Inter Milan 2-0 even without its best player.
Rafinha, who filled in for Messi in the starting 11, and Jordi Alba provided the goals that gave the Spanish team control of their Champions League group with nine points after a third win in as many matches.
"We all had to step up given that everyone, my players, our fans, our adversaries, we all had Messi's absence on our minds," Barcelona coach Ernesto Valverde said. "We always play as a team, and we have a recognizable playing style, but Messi gives us that touch of brilliance. We hope he recovers quickly. I think everyone at the stadium missed him."
Inter has six points in Group B following its first loss.
In the group's other match, Tottenham conceded late to draw 2-2 at PSV Eindhoven, leaving both with only one point.
Before kickoff, Barcelona fans chanted "Messi! Messi!" when images of the Argentina forward appeared on stadium screens, his right arm in a sling after fracturing it in a win over Sevilla at the weekend.
Determined to show Barcelona could cope without him, Messi's teammates dominated Inter with their passing attack and quickly pressured to recover the ball.
But nobody had more to prove to both Barcelona — and Inter— than Rafinha, who was loaned out to the Italian side for the second half of the last season. The 25-year-old Brazilian midfielder is back at Barcelona after Inter decided not to exercise an option to sign him outright, and after media reports linked him to another loan deal this summer than never materialized. He had only played 111 minutes this season before getting the start on Wednesday.
Rafinha constantly harassed Inter's players when they had possession, and he stole the ball from Matias Vecino to spark the move that led to his first goal in 18 Champions League appearances.
After winning the ball near midfield, Rafinha surged forward, passing wide to Luis Suarez on the right flank, who floated in a perfectly timed cross and the hard-charging Rafinha drove the ball past Samir Handanovic in the 32nd minute.
"We knew what Rafinha could give us, from the first to last minute he worked extremely hard," Valverde said. "His goal will help his self-confidence."
Inter had tried sending long balls to striker Mauro Icardi, who threatened to put in a low cross from Ivan Peresic, before Barcelona defender Clement Lenglet drew a reflex save from Handanovic with a header in the 18th.
Inter's halftime substitute Matteo Politano worried Marc-Andre ter Stegen twice shortly after coming on, first with a cross that the Barcelona goalkeeper had to parry and then with a shot that went high.
The action was soon back in Inter's area as Suarez and Lenglet both forced Handanovic to make saves. Philippe Coutinho also hit the crossbar for the hosts before Ivan Rakitic fed a pass forward for Alba to fire home with seven minutes remaining.
"With Messi, they would have caused us more problems, but without him that caused us enough trouble as it was," Inter coach Luciano Spalletti said.
Spalletti was without injured midfielder Radja Nainggolan. But both Perisic and Marcelo Brozovic, who were doubtful for the match, made the starting lineup.
Barcelona next faces Real Madrid in the Spanish league on Sunday.