Mbappe gave PSG a taste of what they would be missing if he
left for Real Madrid, who have made bids to recruit the France striker since
Messi joined on a two-year deal from Barcelona.
The win means PSG top the table with a maximum 12 points.
All 20,545 tickets available were sold at the Auguste
Delaune stadium to see 34-year-old Messi play and the fans, who chanted the
Argentina forward's name, were rewarded in the 66th minute when he replaced the
disappointing Neymar.
Mbappe did not disappoint though in a brilliant performance,
seemingly unfazed by the transfer frenzy surrounding him.
Two days before the end of the window, the 22-year-old made
the difference with his speed and sense of timing, opening the scoring with a
header and rounding off with a clinical finish.
After a stuttering start, PSG got into their groove and
Mbappe put them a head after 15 minutes by heading home from Angel Di Maria's
cross.
But PSG got too comfortable and Reims started to apply some
pressure, with Moreto Cassama's superb strike hitting Keylor Navas's crossbar
three minutes before the break.
Reims celebrated what they thought was a Marshall Munetsi
equaliser five minutes into the second half, only for the Zimbabwean's effort
to be ruled out for offside.
Messi started to warm up after 57 minutes, drawing applause
from the Reims supporters, whom he saluted.
They sang his name just when he was about to come on,
shortly after Mbappe had doubled PSG's advantage from Achraf Hakimi's cross at
the end of a sharp counter attack.
Mbappe combined with Messi, but the former Barcelona striker
was not in the same condition as the Frenchman, having not played a competitive
game since winning the Copa America with Argentina on July 10.
"It was important that he (Messi) started with a
win," PSG coach Mauricio Pochettino told a news conference.
"He brings serenity to the team. His energy and his
optimism trickle down on the rest of the team."
Reims defender Andrew Gravillon crossed Messi's path before
and after the game.
"He's impressive. Last year we were watching him play
the Champions League, now it's a pleasure to have him in our league and it's
also a pleasure to challenge him," he said.
"I went to see him to get his shirt for my little
brother but he didn't give it to me. Maybe next time I'll get lucky."
Earlier, French champions Lille finally got their title
defence going with a 2-1 home win over Montpellier and surprise package Angers
beat visiting Stade Rennes 2-0 to go second on 10 points.
Lille celebrated their first league win of the season thanks
to goals from Yusuf Yazici and Jonathan David. Montpellier ended the match with
10 men after defender Junior Sambia was sent off late in the second half.
Promoted Clermont Foot continued to impress as they kept
their unbeaten record intact after fighting back from two goals down in a 2-2
home draw with Metz. They are third on eight points from their first four
matches.