Arsenal look set for the last 16 of the Women's Champions League after a 4-0 first leg away win against Belarusian team Bobruichanka.
But Bristol Academy and Glasgow City will have tough second legs after both were held to a 1-1 draw on home turf.
Bristol went ahead in the second half but were pegged back six minutes from time by Russian side Energiya Voronezh.
Glasgow took an early lead but had to settle for a draw after Icelanders Valur levelled just before the hour.
Bobruichanka 0-4 Arsenal
Striker Ellen White gave the Gunners the lead after only nine minutes, but the home side then held out until three goals were hit in the final 26 minutes.
Midfielder Jordan Nobbs, substitute Jennifer Beattie and midfielder Katie Chapman were on target to set up what should be a comfortable home leg next Wednesday.
Manager Laura Harvey said: "We dominated without playing particularly well, but I'm delighted to have a four-goal cushion for the second leg."
White shot Arsenal ahead with a neat cross-shot, but despite being in complete control the Gunners were unable to add to their lead before half-time.
Bobruichanka pressed briefly after the re-start, but Arsenal soon regained control and Nobbs doubled the lead with a close range shot from Rachel Yankey's 64th minute cross.
Beattie, who had replaced White, twice missed the target but then made amends when she scored with a well-struck 18-yard shot in the 76th minute.
Chapman completed the scoring from the penalty spot following a foul on left-back Niamh Fahey by substitute Svetlana Astashova two minutes from time.
Harvey added: "We could have got more goals, but we're set up nicely for the second leg and I'm confident we'll go through to the last 16."
Bristol Academy 1-1 Energiya Voronezh
Academy were denied victory by an 84th-minute penalty by Pamela Conti after taking a lead right minutes earlier through Jess Fishlock.
The spot-kick came after Jemma Rose handled on the line, leading to her sending off.
The hosts almost went behind in the eighth minute, after midfielder Conti struck the crossbar with a powerful 18-yard drive.
But they hit back with winger Helen Bleazard wasting a fine chance, before Ann Marie-Heatherson shot over after Fishlock's 15-yard effort had been blocked.
The Russians made the better start to the second half and keeper Siobhan Chamberlain had to make good diving saves from striker Veronica Boquete and substitute Nadezda Bosikova.
But Academy went ahead when substitute Liz Fenlan chased down a through-ball to set up Fishlock to drive in a low shot.
Victory looked on the cards until Conti equalised from the spot and it almost went from bad to worse for Bristol as Boquete sent a fierce 25 yard shot against the bar a minute from time.
Bristol boss Mark Sampson said: "We feel hard done by because we should have won, but we're confident that we can go and get the result we want in the second leg."
Glasgow City 1-1 Valur
Glasgow started brightly and went close on several occasions before striker Lisa Evans gave them a 16th minute lead when she pounced on a loose ball to fire in.
Goalkeeper Claire Johnstone had to keep out an 18th minute Laufey Olafsdottir effort as the visitors looked for a quick equaliser.
But City were soon back on the offensive and both Evans and Jane Ross had shots well saved by goalkeeper Meagan McCray before half-time.
They opened the second half well too, but they were rocked in the 59th minute when Olafsdottir forced the ball in following an indirect free-kick in the penalty area.
As the home side looked to regain the lead Leanne Ross was denied by McCray and both Danica Dalziel and Eilish McSorley sent efforts wide of the target.