The pair have flown thousands of miles to bolster the cause and will start against the ACT Brumbies in Canberra on Tuesday, giving respite to a bruised and battered Lions backline before the first Test against the Wallabies on Saturday.
The selection of Williams, four years after he bowed out of the 2009 Lions tour with a brilliant try against the Springboks and two years after he last played Test rugby for Wales, was a decision that stunned everyone.
Wade's call up from England's tour of Argentina was also a something of a surprise given that he had only made his full international debut the previous week.
At 36 and 22 respectively, Williams and Wade are at opposite ends of their careers but the similarities do not end with the unlikelihood of their presence on the Lions tour.
Bucking the international trend for hulking wingers, they are both a good deal under six foot (1.82m) and weigh in well under the 200lb (90kg) mark but are blessed with great balance, quick footwork and blistering acceleration.
Williams said he had paid "close attention" to Wade's progress and had kept tabs on him through his former Wales team mate Stephen Jones, who is now at Wade's club London Wasps.
"He's a very talented player, new on the scene and already raising eyebrows," Williams told reporters on Monday.
"He's obviously a massive talent, I enjoy the way he plays, he's an aggressive runner, he's very fast, enjoys taking defenders on, my kind of guy really.
"I'm looking forward to playing with him and seeing what he's got. He's more than capable of showing what he's got and being part of this Test series, I think."
The appreciation clearly cut both ways and Wade said it was a "massive thrill" to be able to play alongside the former Wales winger, who scored 58 tries in 87 Tests.
"Shane's one of those players who I've watched and tried to learn a lot off from a distance," he said. "To be able to play alongside side him is probably beyond my dreams.
"I probably wouldn't have got the chance to play against him in my career and to play with him is taking it to the next level."
Wade clearly also has a good dose of the ebullient confidence that carried Williams through a career playing against much bigger men.
"It's just a massive honour to get the call to come over here... I'm happy to be here and if I do get the chance to play in the Test it would probably be the proudest moment in my life," he said, pausing before adding: "So far."
Wade flew 7,500 miles to join up with the Lions after getting the call-up on at the weekend along with England centre Brad Barritt, who had a similar distance to travel from his holiday in California.
"Luckily we have a brilliant backroom staff here at the Lions, they seem to find a way of making the impossible happen," the South African-born centre, who will also start against the Brumbies, said.
"I had the boots delivered this morning and quite strangely I had a gum guard in my toiletry bag. Not sure how that got there."
Williams made the comparatively modest trek of 4,900 miles from Japan, where he has been playing club rugby, after getting the call from Lions backs coach Rob Howley on Saturday and was confident he would be able to make the step up on Tuesday.
"Of course it's going to be difficult but we're professional rugby players," he said.
"We've all got to do our homework tonight and make sure we're be mentally prepared because we don't want to let anyone down. We want to go out there and give it 100 percent and do what we do best.
"Hopefully it won't be too much of a shock to the system (but) if I felt for one second I wasn't going to be ready for this game, or good enough for this game, I'd have told Rob to stick it.
"To be given this opportunity is a dream come true. If by me playing tomorrow, it can help the Lions recover and win that Test on Saturday, then I'm really proud to be part of it."
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