Ellis combines his role at London Irish with the French national team
London Irish defence coach Dave Ellis says he has been providing the team with inside information on Brive, ahead of their Heineken Cup match in France.
Ellis spent two years coaching the former European champions before joining the Exiles in the summer.
He told BBC Berkshire: "I know all the players individually.
"I helped construct their defence over a two-year period, so I've given the information directly to (backs coach)Mike Catt and (head coach) Toby Booth."
Ellis added: "Attack-wise, they're using the same personnel in the same situations, so the information I've provided will be of good use."
Nevertheless, Ellis knows how hard it will be for the Exiles to win in France.
"Brive are past winners - one of the first teams to win the Heineken Cup in the mid-90s - so their tradition is very much towards doing well in the competition," he said.
"Their league form, particularly after losing their first two games in the Heineken Cup, caused them to doubt whether they can proceed.
"But there's going to be a massive crowd and they'll be wanting a performance."
Having worked at Brive, as well as coaching the French national side, Ellis understands the culture of French clubs.
"Unlike the clubs in England, apart from the odd one or two, in France they are still town-based," he added.
"Particularly somewhere like Brive - they represent the whole town because there are no other major sports clubs there, so when Brive are doing well, the whole town is recognised for that."
Ellis also knows the club's strengths, pointing to their "great tradition of scrummaging" and admitting that is one area Irish have talked about.
He said: "If we can get one up on them in that department, it'll have a major psychological effect on their performance.
"Their season has not been a good one, although they've put a couple of good performances together, but their frailties will still be there.
"It's going to be tough, there's no doubt about that. Heineken Cup games always are, particularly going down to France where they are different teams altogether from when they come away from home."