PFC CSKA Moskva's wretched run against FC Porto continued as a 1-0 home defeat ensured the Army Men failed to score against the Portuguese side for the fifth consecutive match.
Unbeaten in the competition this term beforehand, CSKA enjoyed plenty of possession throughout the first leg in Moscow but the lack of an incisive final pass or finish let them down. By contrast Porto's vaunted attack troubled CSKA's defence all evening, although it was midfielder Fredy Guarín who scored the only goal with a fine shot on 70 minutes.
The game had started at a frenetic pace with both forward lines asking a number of questions of their opposing defences. CSKA could have taken the lead after just a minute but Seydou Doumbia fired straight at goalkeeper Helton after being put clean through. The excellent Keisuke Honda was influential for the team in red, creating several chances for Vágner Love that the striker was uncharacteristically unable to convert.
The Portuguese Liga leaders ended the first half the stronger with Falcao proving to be a particular menace, and they might have gone ahead only Igor Akinfeev denied Guarín with a decent reaction stop. CSKA continued to enjoy the advantage in possession after half-time, yet poor finishing undermined their good approach play.
The visitors were content to play on the break and struck on the counterattack with 20 minutes remaining. Substitute Silvestre Varela cut in menacingly from the left flank and played the ball to Guarín who sidestepped Vasili Berezutski to curl a powerful right-footed effort from the edge of the area beyond Akinfeev.
CSKA pushed up in search of an equaliser yet Helton hardly had to make a save. Indeed, it was André Villas-Boas's team who looked more likely to score again. Despite Porto's Cristian Săpunaru blazing a good opportunity over from close range after 87 minutes, the Dragons left the Russian capital with their 100% away record in this season's UEFA Europa League intact ahead of next Thursday's second leg.