They must either win, or get a score draw (and then, 0-0 or 1-1 is not good enough) to go into the final at Hampden Park.
"I didn't play against Ipswich at the weekend because I felt a tightness in my hamstring after last Wednesday's first leg against Bayer Leverkusen but the rest has done the trick and I'm raring to go on Tuesday night," said Giggs today on his official website.
"If we didn't have such a crucial game this week I could have started at Portman Road but we decided it wasn't worth the risk."
"There's no denying that we've left ourselves a lot to do after the first-leg result. We always seem to make things difficult for ourselves at this stage of the competition and this season has proved no different.
"We did things the hard way in the semi-final against Juventus in 1999 and if we are to reach the final this year, we will have to find another performance like we did in Turin.
"Juventus were one of the best sides in Europe at the time and the memories of going to the Delle Alpi and winning 3-2 to reach the final is still fresh in our minds and a massive confident boost. If we can win there when the pressure is on, we can definitely do it again in Germany, especially because I think we're even more dangerous going forward than we were three years ago.
"Not that we enjoy leaving ourselves in this kind of position. It's true that you often see the very best of United when we're under pressure or the chips are down and while it might be exciting for the fans, we'd much rather do it the easy way.
"I think a lot of people have underestimated Leverkusen throughout this Champions League campaign but we still felt we underperformed in the first leg at Old Trafford. We feel we're capable of moving up at least a couple more gears from Wednesday and we'll have to see whether they've got something more up their sleeve. If we perform as we know we can, they'll need to improve if they're going to live with us.
"Ironically, with the tie finely balanced, I think it could work to our advantage playing the second leg away from home. We now know exactly what is now required if we're to make the trip to Glasgow and that helps to ease some of the pressure because no-one is worrying about all the possible permutations of a first-leg result. We know we need to win and that means scoring goals. If we leave space at the back as a result, then so be it."