Chelsea are in a strong position against Russian side Rubin Kazan after winning the first leg 3-1 at Stamford Bridge, but Tottenham have work to do following a 2-2 draw with Basel at White Hart Lane.
Newcastle are in trouble following a 3-1 defeat to Benfica in Lisbon, while Fenerbahce beat Lazio 1-0 in Istanbul.
Chelsea got off to a fantastic start in west London, opening the scoring 16 minutes in when Fernando Torres -- sporting a face mask to protect a broken nose -- stabbed in a David Luiz pass.
Victor Moses then finished superbly on the half-volley to double the Blues' lead just after the half-hour mark.
Bebras Natcho netted a penalty after John Terry was penalised for handball to give the Russians a precious away goal just before half-time, but much-maligned Spanish striker Torres headed in a cross from compatriot Juan Mata 20 minutes from time to give Chelsea an important cushion.
Chelsea coach Rafael Benitez praised Torres.
"It's good for his confidence. His work-rate was really good. I'm pleased for him."
Across London, Spurs endured a much less comfortable evening against the Swiss champions.
Against a side challenging for a top-four place in the Premier League, Basel were a constant threat going forward, and took the lead on the half hour when Valentin Stocker converted the rebound after captain Marco Streller's initial effort struck the post.
The Spurs fans were stunned when Basel doubled their lead four minutes later, Fabian Frei heading in.
Emmanuel Adebayor reduced the deficit before half-time, forcing the ball in after a Scott Parker shot had deflected into his path.
Gylfi Sigurdsson then levelled in the 58th minute, his powerful effort deflecting into the net off Fabian Schaer.
The concession of two away goals means Andre Villas-Boas' Tottenham have work to do to progress and their evening ended on a sour note when Gareth Bale was stretchered off with a serious-looking ankle injury.
"He rolled on his ankle, at the moment there is a lot of pain, but hopefully it's not as bad as it could have been," Villas-Boas told BBC Sport.
Newcastle got off to a terrific start at the Estadio da Luz, taking the lead in the 12th minute when Papiss Cisse turned in a Moussa Sissoko cross, and they almost netted again soon after, Cisse's shot deflecting off Ezequiel Garay and hitting the post.
Two minutes after that, Benfica were level, Rodrigo stabbing home after Tim Krul had beaten out a powerful shot by Oscar Cardozo.
Cisse hit the post again at the start of the second half on a wet night in Lisbon, but Newcastle only had themselves to blame when they conceded again in the 65th minute.
Davide Santon was short with a pass back to Krul, and Lima pounced to round the 'keeper and slide the ball home.
Three minutes later Benfica won a penalty when Steven Taylor handled in the area, and Cardozo scored to give the Portuguese league leaders a 3-1 victory.
Newcastle coach Alan Pardew said qualifying would now be a very tough call.
"If we'd taken 2-1 you'd like to think we'd have a fantastic chance but it's an uphill chance now," he told ITV4.
Fenerbahce are in a strong position to progress to the last four after a Pierre Webo penalty 12 minutes from the end and a Dirk Kuyt effort in stoppage time saw the Turks beat Lazio 2-0 in Istanbul.