Dries Mertens started this season where he left off the last, setting Napoli on its way to a 2-0 win over nine-man Nice in the first leg of their Champions League playoff on Wednesday.

Mertens scored more than 30 goals last season for Napoli, with five of them in the Champions League. And it took the Belgium international less than 13 minutes to open his account for this campaign.

Mertens sprung the offside trap to race onto a through-ball, take it past onrushing goalkeeper Yoan Cardinale and slot it into the empty net.

The 30-year-old forward was instrumental in Napoli's second, winning a penalty when he was tripped by Christophe Jallet just inside the area. Jorginho converted the spot-kick in the 70th minute.

Nice's night went from bad to worse 12 minutes from time when midfielder Vincent Koziello was shown a straight red card for a challenge on Napoli's Piotr Zielinski and teammate Alassane Plea followed him off the pitch after receiving a second yellow for dissent.

In other first-leg results, Celtic beat Astana 5-0, while Sevilla won 2-1 in Turkey against Champions League newcomers Istanbul Basaksehir. Olympiakos and Hapoel Beer-Sheva both came from behind to win 2-1, against Rijeka and Maribor respectively.