Edinburgh and Cardiff Blues are level on 17 points in Pool 2, the Scottish club ahead courtesy of a superior overall try count, but if things remain level on match points after the end of the group stages then it will come down to match points in the two fixtures between the clubs with the Blues 5-4 better off thanks to the losing bonus point they banked at Murrayfield in Round 4.
"It was a great win at the Madejski but we still have to back it up on Sunday," said Warburton.
"It's going to be a funny one in that we'll have to give it our all but we won't know until the final whistle if it's good enough or not. All we can do is focus on ourselves and do everything we can to make sure we get that win.
"It's going to be another tough encounter against Racing. We don't know what sort of side they'll bring over as they are out of the competition now but whatever team they bring over, we'll be just as motivated to make sure we get the four points.
"If they bring a strong team, then that's fine - it's better to beat the best than get through an easier way.
"And looking back at things that result in France in Round 1 was key. It has given us so much momentum going into the rest of the games although there was that blip up in Edinburgh where we let ourselves down."
Pools 2 and 4 are the groups with two clubs on four wins each after five rounds - bonus points all that separate Toulouse and Harlequins - and Warburton is adamant that the Blues' season will stand or fall on their Heineken Cup record.
"Normally teams would think they could well be in the quarter-finals with four wins at this stage but it's been a tough group and Edinburgh are pushing us all the way," he said.
"I don't think a lot of people expected this scenario, especially Racing having three home defeats. It's very tough to go to France and win but that's opened the group right up and I'm sure Edinburgh will fancy their chances next week.
"They will throw everything at Irish so it's going to be a really close one to call.
"And the Heineken Cup is special. You still give your all for the PRO12 games but the Heineken Cup has something extra. The changing room always has a bit more of a buzz and so does the week's preparations.
"Getting a home semi-final is a huge incentive. If we could get five wins I think we probably would be one of the top four qualifiers and a home quarter-final draw would be fantastic, it would be massive.
"I was up in the stand for that semi-final in 2009 when over 44,000 turned up for that Leicester game in the Millennium Stadium. That's the sort of game in which you want to be involved and in the last two years we haven't quite been there. We had a good run in the Amlin Challenge Cup when we won that but you really want to win the big one and that's the Heineken Cup."