Shabani Nonda's late strike put Blackburn in a strong position despite defeat in the first leg of their Uefa Cup tie with Bayer Leverkusen.
Leverkusen's Jan-Ingwer Callsen-Bracker opened the scoring with a far-post header, before David Bentley levelled when his free-kick took a deflection.
Carsten Ramelow's shot was deflected in and Bernd Schneider superbly flicked in a third ten minutes after the break.
But Nonda volleyed in late on to give Rovers hope for next week's second leg.
Rovers went into the match in confident mood, and lined up in an attacking 4-4-2 formation, with Jason Roberts earning his first taste of European football.
Leverkusen were missing their first-choice centre-backs Roque Junior and Juan - and within two minutes their defensive fragility became apparent.
Bentley delivered a superb cross into the box but an unmarked Benni McCarthy missed his kick.
McCarthy later headed off target, from another Bentley cross, and also made a hash of a pull-back to allow two more opportunities to go begging.
Unfortunately for the South African, he was also out-of-touch defensively, and when he lost his man at the back post, Leverkusen took the lead.
McCarthy's lapse allowed Callsen-Bracker an easy chance to head the opener.
Blackburn pushed forward in numbers in search of the equaliser, but also left themselves vulnerable to a counter attack.
Andriy Voronin screwed a shot wide after a slick Leverkusen move, while at the other end, Aaron Mokoena fired an effort past the upright.
Then Rovers got back on level terms when Bentley took aim from 25 yards and his free-kick took went in via the wall.
But Rovers' fortune turned against them five minutes later when Ramelow's shot took a wicked deflection off Ryan Nelson's chest leaving keeper Brad Freidel no chance.
And things soon got worse for Rovers after the break.
Gonzalo Castro crossed in low from the right just behind Schneider, who managed to deftly flick the ball with his heel and send it in off the post.
The lively Kiessling almost added to Leverkusen's advantage but was twice denied by Freidel as the hosts dominated.
Rovers lacked a threat up front, with Roberts off the pace, and a lone Bentley shot all they could muster.
That was until substitute Nonda smashed in a volley off the underside of the bar after Rovers managed to put Leverkusen under pressure for the first time in the half.
Blackburn manager Mark Hughes:
"We were not able to affect the game and dictate the pace of it as we would have wanted but the second goal gives us a real chance.
"We were lacking physically because some players were unavailable to us but some of them will be back next week and I am sure we will produce a different performance."
Bayer Leverkusen: Butt, Haggui, Callsen-Bracker, Rolfes, Castro, Schneider, Barbarez, Ramelow, Babic, Voronin, Kiessling (Freier 85).
Subs Not Used: Fernandez, Stenman, Barnetta, Athirson, Papadopulos, Camdali.
Booked: Barbarez.
Goals: Callsen-Bracker 18, Ramelow 43, Schneider 56.
Blackburn: Friedel, Warnock, Mokoena (Todd 90), Henchoz, Nelsen, Bentley, Kerimoglu, Dunn (Peter 65), Emerton, Roberts (Nonda 69), McCarthy.
Subs Not Used: Enckelman, Khizanishvili, Jeffers, Gallagher.
Booked: Mokoena.
Goals: Bentley 39, Nonda 86.
Att: 22,500
Ref: Pieter Vink (Holland).