Mertens rounded Nice goalkeeper Yoann Cardinale after racing on to a ball over the top to fire into an empty net in the 13th minute.

And Christophe Jallet then fouled Belgium international Mertens in the 70th minute to concede a penalty, which Jorginho scored to seal the win.

Nice were not helped by the absence of Mario Balotelli, who is injured, and new signing Wesley Sneijder, who is not yet match fit.

Celtic confidently planted one foot into the Champions League group stages with a 5-0 thumping of Astana in the first leg of their play-off at Parkhead.

Returning midfielder Tom Rogic's strike in the 31st minute was helped into his own net by defender Evgeni Postnikov before Scott Sinclair added a second three minutes before the interval.

Sinclair notched his second on the hour mark with further goals from winger James Forrest and striker Leigh Griffiths -- his might have taken a deflection off Igor Shitov -- for a result which in no way flattered Brendan Rodgers' men.

Celtic knocked the Kazakhstan outfit out in the third qualifying round last season on a 3-2 aggregate and only a remarkable turnaround next Tuesday in Astana will prevent a repeat.

Wissam Ben-Yedder scored in the 84th minute to earn Sevilla a 2-1 victory against Istanbul Basaksehir.

The Spanish side had taken a 16th-minute lead through Sergio Escudero but were pegged back by former Southampton and Juventus winger Eljero Elia's 64th-minute equaliser.

However, Ben-Yedder grabbed the goal which gave Sevilla an important away win.

Alaixys Romao scored in the third minute of added time as Olympiakos left it late to beat Rijeka 2-1.

Croatian champions Rijeka had taken a first-half lead through Brazilian striker Heber on 41 minutes.

But Vadis Odjidja-Ofoe levelled the scores in the 66th minute before Romao gave the Greek side a narrow advantage ahead of the second leg.

And in the other game Hapoel Be'er Sheva ran out 2-1 winners against Maribor.

Marco Tavrares put visitors Maribor ahead on 10 minutes but Anthony Nwakaeme's 12th-minute strike pulled Hapoel level and Shir Tzedek won it with a penalty in first-half stoppage time.