Victory against the Warriors at the Arms Park on Friday night is essential if the Blues are to remain in contention to qualify from Pool Two.
Only one point separates leaders Exeter from bottom-placed Cardiff, who blew the group wide open by beating reigning European champions Toulon 19-15 in October.
"The next two weeks will go a long way to deciding our fate in the Heineken Cup," Blues director of rugby Phil Davies said.
"It's vital we start strongly and get another crucial victory at the Arms Park.
"Our win over Toulon will always live long in the memory. It was a famous day for our region.
"Now it is vital we build on that result because the pool is wide open after two games and every team is chasing top spot."
Glasgow skipper Al Kellock will make his 50th Heineken Cup appearance in the first match of a double header that head coach Gregor Townsend views as key to the Warriors' quarter-final aspirations.
"We know the outcome of these game will be pivotal to our hopes of progressing in the tournament," Townsend said.
The Ospreys' faint hopes of reaching the knockout stages will be all but over should they fail to win at French champions Castres on Friday night.
The Welsh region have failed to register a single point after two rounds and with Leinster and Northampton also in Pool One, the odds are stacked heavily against them.
"Castres are back in the top four of the Top 14 so their quality is absolutely clear," head coach Steve Tandy said.
"After a disappointing opening two rounds we know that we've got to put in some excellent performances over the next two weekends and that's what we are targeting."
Lions lock Alun Wyn Jones returns to lead the injury-hit Ospreys, who also welcome back Wales stars Dan Biggar, Justin Tipuric and Ryan Jones.
Newport Gwent Dragons host Bordeaux-Begles in Pool Two of the Amlin Challenge Cup knowing defeat would effectively end their chances of progressing beyond the group stage.