London - Athletic Bilbao's nightmare start to the season continued as their chances of progressing to the last 16 of the Champions League were severely dented by a 2-1 loss to BATE Borisov on Tuesday.
The Belarussian champions had been beaten 6-0 by Porto in their opening game, but bounced back in style as first-half goals from Denis Polyakov and Aleksandr Karnitski handed them the three points.
Aritz Aduriz's strike just before half-time had given Athletic some hope, however, they now languish at the bottom of Group H as their winless streak in all competitions extends to six games.
Porto's late equaliser in a 2-2 draw away to Shakhtar Donetsk in the night's other game in the group means BATE move into second place, a point ahead of the Ukrainians.
The hosts made the breakthrough on 18 minutes when a corner to the near post was flicked and the unmarked Polyakov had the easiest of tasks to slam the ball home from close range.
BATE were desperately unlucky not to double their advantage on the half hour mark as Nikolai Signevich's sweetly struck volley came back off the inside of the post and rebounded to safety.
However, misfortune then struck Athletic 11 minutes later when Karnitski's weak strike was deflected past Gorka Iraizoz by Andoni Iraola.
Athletic were handed a lifeline a minute before half-time when Iker Muniain fed Aduriz and he fired home into the far corner.
Yet, despite coach Ernesto Valverde making two attacking changes at half-time by bringing on Oscar de Marcos and Markel Susaeta, the Basques failed to built on that momentum.
Indeed it was BATE who ought to have put the game to bed on the break in the second-half as Signevich firstly shot meekly into the arms of Iraizoz and then fired an even easier chance over from close range.
Athletic's only serious effort on goal after the break came eight minutes from time, but BATE 'keeper Sergei Chernik turned Susaeta's piledriver behind to secure a famous victory.