The Cork wing had spoken of his disappointment of missing out on the initial selection, but he will capitalise on the misfortune of Bowe after the Ulster wing broke a bone in his hand against the Queensland Reds.
Lions coach Warren Gatland and his staff were forced into discussions about a replacement for Bowe, who has since had an operation on his hand and could still feature, with 23-year-old Zebo appearing to have received the nod ahead of a selection from England trio Mike Brown, Ben Foden and Christian Wade.
"The surgeon who spoke to him said that if everything goes all right it could be just a couple of weeks. Once the plate is put in, the bones are fixed, basically," Gatland said.
Bowe's blistering form suggests he would have been a shoo-in selection for the opening Test on June 22, but although that game now appears beyond him, the second Wallabies encounter a week later could conceivably feature on Gatland's selection radar.
The surgery was to stabilise a bone fracture in his hand, and the Lions say his condition will be assessed over the next few days.
Zebo played for 75 minutes in Ireland's hard-fought 15-12 win over the States before being replaced by Felix Jones. It was his sixth cap for his country and his first since a Six Nations defeat to England. He will depart Texas for Australia on Sunday night after receiving a phone call from tour manager Guy Richardson when he arrived back to Ireland's team base after the game.
"I heard this morning that Tommy had an injury on one of the social media sites so I just had to stay focused and keep myself away from it, just try and go out and play well tonight. We got the win which was very important to us," he said late on Saturday night.
"I'm absolutely over the moon. It is the best news I could ever have dreamed of. As a professional (Irish) rugby player the ultimate goal is to be a British and Irish Lion. Hopefully I'll get the chance to do that if I get my cap. That is something I have to work towards now."
The Corkman admitted that the foot injury that ended his Six Nations campaign had derailed his Lions ambitions, but believes he has overcome that disappointment and is ready to hit the ground running Down Under.
"It was a bit of a hiccup but I only missed a couple of games, I was only out for six weeks in the end but I suppose the lack of international game time was a little bit of a setback," he said. "But that's all in the past now. Exciting times ahead, hopefully."
There is still a degree of optimism that Bowe could recover quickly and possibly be involved in the Test series against Australia.
"We just want to see how the operation goes," Gatland said. "The surgeon who spoke to him said that if everything goes all right it could be just a couple of weeks. Once the plate is put in, the bones are fixed, basically."
England prop Alex Corbisiero will make his Lions debut against a Combined Country XV in Newcastle on Tuesday.
Corbisiero, who only arrived in Brisbane on Saturday from England's tour of Argentina, will start in a team captained by Ireland centre Brian O'Driscoll. Corbisiero's fellow tour replacement Ryan Grant has been named on the bench, while Scotland full-back Stuart Hogg is handed fly-half duties.
Props Cian Healy (ankle ligaments) and Gethin Jenkins (calf muscle) are set to fly home due to tour-ending injuries. The line-up for Tuesday also includes Wales centre Jamie Roberts, England prop Dan Cole, Scotland lock Richie Gray and Ireland number eight Jamie Heaslip.
Fly-half Jonathan Sexton meanwhile has had a scan on his hamstring after he reported tightness in it during the Reds game, but there are not thought to be any issues surrounding him.
"The Reds game was always going to be a big challenge, and I was delighted at the victory and the way we were tested," Gatland said. "It was a very physical match, as we knew it would be. We now move on to Newcastle and another challenge.
"This team to play Country includes three players - Richie Gray, Alex Cuthbert and Stuart Hogg - who are starting their second game in a row, plus another, George North, who came off the bench early against the Reds. This is the nature of Lions tours as we adapt to injuries and playing twice a week."
Lions manager Andy Irvine added: "We are delighted to have kept our unbeaten record intact. We were pushed all the way by an extremely skilful and committed Reds team that played some brilliant intuitive rugby. However, I was incredibly proud of the way we responded and how we defended right to the bitter end."
British and Irish Lions team: S Maitland (Scotland); A Cuthbert (Wales), B O'Driscoll (Ireland, captain), J Roberts (Wales), G North (Wales); S Hogg (Scotland), C Murray (Ireland); A Corbisiero (England), R Hibbard (Wales), D Cole (England), R Gray (Scotland), I Evans (Wales), S O'Brien (Ireland), J Tipuric (Wales), J Heaslip (Ireland)
Replacements: R Best (Ireland), R Grant (Scotland), M Stevens (England), A-W Jones (Wales), T Faletau (Wales), M Phillips (Wales), J Davies (Wales), L Halfpenny (Wales)