The 30-year-old has notched more clean sheets than anyone else this season (eight in 16 games) - helping surprise package Dortmund to the top of the Bundesliga with an impressive 11-point lead over Bayer Leverkusen.
This way to Villa Park: Roman Weidenfeller is set to join Houllier's men at the end of the season
Despite the club being on track for their first Champions League qualification since 2003, Weidenfeller is set to let his contract expire at the end of the season and join Villa.
Gerard Houllier's side are conversely languishing in the bottom half of the Barclays Premier League, but Weidenfeller is keen on testing himself abroad after what will be nine years at Dortmund.
The former Kaiserslautern keeper has been offered a four-year contract to stay put but can command a higher salary in England.
No 1: Brad Friedel has been a consistent Premier League performer for 10 years
Current keeper Brad Friedel has been one of the Premier League's most consistent performers in goal over the past ten years but is out of contract at the end of the season, and will be 40 next May.
Friedel's understudy and United States international colleague Brad Guzan remains relatively inexperienced in terms of Premier League appearances, while youngsters Elliot Parish and Benjamin Siegrist are the other goalkeepers on the books at Villa Park.
Under pressure: Villa boss Gerard Houllier
The deal would represent a real boost to former Liverpool boss Houllier, who has been struggling to win over the Villa fans since he was appointed manager in September.
Houllier angered the club's core support by paying an emotional tribute to the Reds before and after his return to Merseyside last Monday, a trip that ended in a feeble 3-0 defeat for his side.
The Frenchman last month brought in former Arsenal star Robert Pires on a six-month contract, but the 37-year-old has so far failed to live up to the lofty name he made for himself during his spell in north London.
The pressure on Houllier eased slightly on Saturday after Villa snatched a vital 2-1 win at home to West Bromwich Albion thanks to Emile Heskey's second-half header, but the club still languishes in 14th spot in the Premier League, just four points above the relegation zone.
Aston Villa midfielder Ireland set for crunch talks with HoullierAston Villa 2 West Brom 1: Houllier rises to win some breathing spaceHoullier finally apologises for Anfield gaffe as fan anger grows at Aston VillaASTON VILLA FC