Renne's Giovanni Sio equalised in the 80th minute as he appeared to control Jeremie Boga's effort with his hand and scored from point-blank range to cancel out Helder Costa's 14th-minute opener.
"I think we played well," Monaco's Bernardo Silva told Canal Plus, "we opened the scoring and controlled the match, but unfortunately we couldn’t secure the three points.
"We now have to think about the next match and do everything possible to take second place."
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The draw left Monaco in third on 61 points, two clear of fourth-placed Nice and level on points with fellow ChampionsLeague hopefuls Olympique Lyon, who won 3-2 at Toulouse on Saturday and have a better goal difference.
Ten-man Marseille, held 1-1 by Nantes at the Velodrome,extended to 15 their club-record run of home matches without victory and remained just five points above the relegation zone with three matches left.
Nantes went ahead after half an hour when Marseille defender Nicolas Nkoulou headed an own goal past goalkeeper Steve Mandanda who had Leo Dubois’s cross into the six-yard box covered.
Marseille, managed by interim boss Franck Passi, equalised through Florian Thauvin from a pass by Javier Manquillo four minutes into the second half, then had midfielder Alaixys Romao sent off for kicking Yacine Bammou.
Ajaccio moved out of the relegation zone afterdefeating Bastia 3-2 in a thrilling Corsican derby while Montpellier, who lost Hilton to a 41st-minute red card, eased their own relegation concerns by beating bottom club Troyes to move up to 11th.
(Reporting by Ed Dove, editing by Ed Osmond)
