​The crucial Champions League play-off ties have kicked off with the first legs of these do-or-die clashes taking place on Tuesday and Wednesday night.

Among the sides taking part were the last season's semi-finalists Ajax, who drew blank in Cyrpus, while giants of Greek football Olympiakos took a three-goal advantage away from their first leg clash against Krasnodar.

Beaten by ​Tottenham in the semi finals of last season's competition, only one match stands in Ajax' way before they can embark on another ​Champions League fairytale after a 0-0 draw away at Apoel Nicosia.

The Dutch side dominated proceedings, registering 72% possession, but were unable to land the killer blow against the Cypriots, and saw defender Noussair Mazraoui see red for a second bookable offence with ten minutes left to play. Nevertheless, they will head into the return leg in Amsterdam confident of seeing off Thomas Doll's men.

Celtic's defeaters CFR Cluj were handed a two-legged affair with Czech side Slavia Prague as reward for beating the Bhoys, but their tie started in the worst way possible as they fell to a 1-0 home defeat thanks to Lukáš Masopust's 28th minute strike.

Its advantage Club Brugge in their quest for a Champions League spot after Hans Vanaken's first half penalty gave them a 1-0 lead heading into the return leg in Belgium.

Greek champions Olympiakos put one foot in the tournament's group stages with a 2-0 win over Russian outfit Krasnodar, as goals from Miguel Angel Guerrero and a Lazar Randelovic brace meant they head into the second leg with odds firmly in their favour.

The same applies to Dinamo Zagreb, who made sure Rosenborg will have their work cut out to successfully get through the tie. First half goals from Bruno Petkovic and Mislav Orsic meant their 2-0 will put them in good stead ahead of the return leg in Norway.

One tie that remains firmly in the balance is the one between Young Boys and Red Star Belgrade, who played out a 2-2 draw in Switzerland on Wednesday night. Roger Assale gave the hosts the lead, but they were pegged back by strikes either side of half-time from Milos Degenek and Mateo Garcia. It fell to veteran striker Guillaume Hoarau to level matters, with his penalty leaving all to play for in Serbia.

The second legs for all the Champions League play-off ties will be played on August 27/28, with the draw for the group stages proper of the competition taking place on August 29 in Monaco.