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However, the Swiss side's chances were hindered by Serey Die's early sending-off for what was deemed to be serious foul play by referee Deniz Aytekin, although replays suggest that the midfielder was unlucky to receive a straight red card.
Ludogorets almost made their one-man advantage count midway through the half when Mihail Aleksandrov's cross reached Roman Bezjak, who saw his subsequent shot blocked by the visitors' defence.
Basel didn't look to retreat after the loss of Die and had an opportunity to nick a goal on 27 minutes but Derlis Gonzalez was tipped away as his drive headed towards the top corner.
Later in the half, the Bulgarian side again threatened to break the deadlock as Fabio Espinho unleashed right-footed strike from the edge of the box that almost crept inside Vaclik's post.