With Willy Boly suspended, Vallejo and Romain Saiss are the contenders to take his place on the left-hand side of defence against the Blues.
It would be a high-profile debut, with Molineux celebrating its 130th anniversary, but the Spaniard is no stranger to pressure having come in on loan from Real Madrid – and has settled in well under Nuno Espirito Santo.
“My experience here has been fantastic,” said the 22-year-old stopper.
“At first when I arrived here, everybody was nice to me, and it made it easier.
“The captain Conor Coady sent me a (text message) to say welcome, and then my first training session here went fine, so I’m excited about this challenge.
“Real Madrid strongly recommended I should come to the Premier League to improve my football, and I think it was the right decision.
“I feel really wanted here. Nuno called me saying he needed me to come and help the team, and I’ve been very happy. Things couldn’t get any better.
“We are going to have a lot of games, and we are a small squad, so everybody is very important here, and I hope to play a lot of games for Wolves.”
Vallejo, who captained Spain Under-21s to European Championship glory in the summer, came in on loan from Real for the season, having previously had loan spells at Zaragoza and German side Eintracht Frankfurt.
And those stints gave him a taste of how Wolves operate.
“We have a three-line defence, and I’m used to that position,” said Vallejo.
“At Zaragoza, and then at Frankfurt, I played in that system. At Wolverhampton, I tend to play more on the right side, but I can genuinely play on any of the three defensive positions.
“The truth is I feel very at ease in Nuno’s system.
“I am ready, I’m training well, and I’m prepared when the coach decides I should start.”
Meanwhile, a host of club greats are set to take part in the anniversary celebrations tomorrow.
Derek Parkin, Kenny Hibbitt, Steve Bull, John Richards, John McAlle, Geoff Palmer, Phil Parkes and Andy Thompson are among those who have been invited as Wolves look to keep up the party atmosphere by beating the Blues.