Celtic will have only complacency to guard against when they make the long trip to Kazakhstan for Tuesday’s Champions League play-off second leg. Their cause in the east end of Glasgow was assisted by two Astana own goals but with five in total to protect them in the return game, their place in the group draw is all but assured.

There was a big element of controversy about the game’s third goal, and Scott Sinclair’s second, on the hour. It was scored as a member of each side lay prostrate on the turf following a bad clash of heads, but play was allowed to continue and the Celtic attacker took full advantage.

The Astana manager, Stanimir Stoilov, said: “If I were the referee I would have stopped the game. First of all, we have to think about the health and safety of the players.”

If that was perhaps a break for Celtic, they were deserving of their big win and Brendan Rodgers, who says he expects his attacking midfielder Stuart Armstrong to sign a new contract imminently, said: “It was an outstanding team performance. We scored five goals and we missed one or two chances. To do it at this level of competition and show this level of composure made me really proud.

“Every game in this qualification is a pressure one, but the pleasing thing is the calmness with which the players handled it. The first goal was very important for us, like it is at any level, and we really settled after that.

“It was a complete performance in many aspects, and now we understand we need to get the job done over there in the second game.”

Sinclair, whose goals either side of half time played a big part in the victory, said: “You just keep pushing and pushing. That’s what we did and it was a great win. The atmosphere is always unbelievable. It’s always important that you win the game, but the thing for us is that we want to step our games up and I think everybody did that in the team.”

Rodgers made two changes from the side which had beaten Partick Thistle on Friday night, and both Leigh Griffiths and Tom Rogic made huge impressions on the tie. Celtic had two excellent chances to take the lead in the opening seven minutes but both were spurned – Sinclair and Griffiths sending their efforts wide from in front of the goal.

Astana had their moments and the packed home crowd was starting to get restless when Celtic, somewhat unexpectedly, took the lead. Mikael Lustig fed Rogic and he cut in past two defenders before firing in a shot beyond the goalkeeper Aleksandr Mokin. Central defender Evgeni Postnikov ensured the ball ended up in the net with a failed attempt to clear just inside the far post.

Celtic went two ahead just before the interval. A slack Astana pass let Sinclair in behind the defence and he shot across Mokin from the right-hand side of the penalty area to double the advantage.

With the dynamic of the game having totally changed, Celtic started the second half probing for the third goal which would in all likelihood kill off the tie – and Sinclair scored it while Rogic and Yuri Logvinenko were crumpled on the turf with head injuries after contesting a high ball just inside the Astana half.

The Romanian referee, Ovidiu Hategan, was in line with the players but nevertheless waved play on, allowing Griffiths to feed Sinclair and he again beat Mokin to make it 3-0.

Both stricken players required lengthy treatment, with Rogic playing no further part in the game and being replaced by Callum McGregor. A groggy-looking Logvinenko, his head heavily bandaged, then received a yellow card for his role in the incident, and after being examined on the touchline he was also replaced.

Rodgers later gave Rogic a clean bill of health, saying he was “fine”.

What was already a bad night for Astana became catastrophic for their Champion League prospects when they conceded two further goals in the last 11 minutes. Griffiths had not been having the best of evenings in trying to get on the scoresheet, but he was again the provider for Celtic’s fourth. A subtle flick gave Forrest a sight of goal and he scored with a low shot from a tight angle.

With two minutes to go, the little striker again played a big part in ensuring Astana will need a footballing miracle on Tuesday. His shot took a deflection off the Astana captain Igor Shitov for the fifth goal which, surely, ensures his side’s place in the group draw.

Napoli take advantage against nine-man Nice

Napoli scored from a disputed penalty to beat Nice 2-0 in the first leg of their Champions League play-off on Wednesday as the French side had two players sent off in quick succession late on. Dries Mertens put Napoli ahead in the 13th minute and Jorginho converted a penalty in the 70th after Christophe Jallet tripped Mertens, although replays suggested it happened just outside the penalty area.

Nice were reduced to nine men in the 79th minute when Vincent Koziello was given a straight red card for a studs-up challenge on Piotr Zielinski and Alassane Plea was given a yellow card for protesting – his second of the game.

Elsewhere, a late goal from Wissam Ben Yedder gave Sevilla a 2-1 win at Istanbul Basaksehir. Olympiakos came from behind to beat Rijeka 2-1 at home with a last-minute goal from Jacques Alaixys Romao in another of the ties, while Hapoel Beer Sheva saw off Maribor 2-1 at home. Reuters