Barcelona and Newcastle meet at Camp Nou in the last 16 of the Champions League on Wednesday night after a 1-1 result in the first leg.
If Newcastle wishes to reach the Champions League quarter-finals for a third successive season they must bypass the La Liga leaders who have not been perfect this season.
The Spanish giants lost two of their eight league phase matches, against Paris Saint-Germain and Chelsea and only clinching a top-eight finish when they came from behind to beat FC Copenhagen on the final match day.
Speaking to Betfair, Shearer revealed that he thinks Newcastle do have a chance at pulling off a stunning result.
“Newcastle need to defend well at the Nou Camp. They're going to suffer in terms of possession, and that's the key thing. Barcelona have played 11 times in their new stadium already and won 11. So that's going to be a tough thing.
“They're going to have to defend as well as they did, even better, I guess, in the return leg. And then when they do get the chance, they're going to have to hit them on the break. Barcelona do give you chances. If you play against their defensive system right with that high line, you will get in.
“Newcastle got in behind a lot of times and they will get chances. It's just how many they can keep out at the other end, because I don't think it'll be a clean sheet. They've given themselves a chance. It could have been a lot better, and their performance should give them a lot of encouragement, but I do think it will be very different at the Nou Camp.”
Barcelona have suffered defeat in just two of their 37 home games against English sides in UEFA competition and a Newcastle win would be one of the most notable moments in the club’s history.