Gelson Martins gave the principality side the perfect start in the 14th minute at the Stade Louis II when he turned in a cross by Caio Henrique.

Niko Kovac's side, who finished third last season, were looking to build on their 2-0 win away to Sparta Prague in the first leg of their Champions League third qualifying round tie in midweek.

However they were pegged back shortly before half-time as defender Jean-Charles Castelletto headed in the equaliser for a Nantes side who only avoided relegation at the end of last season in a two-legged play-off.

After most of the last campaign in France was played out behind closed doors, fans made their return for this game but all spectators aged over 16 needed to show a valid Covid health pass to prove they were fully vaccinated or had tested negative for the virus.

The crowd of 7,000 at the Stade Louis II, which included Prince Albert of Monaco, saw a trio of new signings in Monaco's starting line-up.

Bayern Munich loanee Alexander Nuebel was selected in goal and Brazilian midfielder Jean Lucas featured along with Dutch under-21 international striker Myron Boadu, who was signed from AZ Alkmaar for a reported 17 million euros ($20.1 million) on Wednesday.

Monaco play the second leg of their Champions League tie against Sparta on Tuesday. If they progress they will face a two-legged play-off against either Genk or Shakhtar Donetsk for a place in the group stage.

Last season's Ligue 1 runners-up Paris Saint-Germain kick off their campaign on Saturday away to newly-promoted Troyes.

Champions Lille are in action on Sunday away to Metz.