Venezuelan hitman Miku netted his first goal for the Scottish champions in the 2-2 draw with Dundee United at Tannadice.
The 27-year-old put himself in the frame for a start in the Group G showdown with Tito Vilanova's superstars on Wednesday night with his fine effort.
Hoops manager Neil Lennon has serious injury doubts about a string of important first-team players ahead of the Barca clash at Parkhead.
James Forrest, Hooper, Emilio Izaguirre (all hamstring), Thomas Rogne (calf) and Georgios Samaras (ankle) are battling to be fit.
But teenage ace Watt, who set up the first goal and scored the other, believes his new team-mate can do a job against the Catalan giants.
Miku spent the first eight years of his career in Spain and netted 12 goals for Getafe in La Liga last season.
And Watt said: "We have got a big squad at Celtic and everybody in it is a quality player. Hopefully, we can do as well as we can against Barcelona.
"Miku certainly showed everybody what he was all about yesterday. He came on, was very lively and scored a great goal. I was happy for him when he got his goal.
"He is a quality player and he is going to show that with goals now. The best is still to come from him. He knows what playing against Barcelona is all about. Hopefully he does well against them if he plays."
Meanwhile, Watt is confident Celtic's dramatic late collapse against United – they conceded two goals in the final few minutes – will not dent their confidence going into the Barcelona match.
He said: "It is just one of those things. We just have to deal with it. I would say we were the better team for the 90 minutes. Well, for 85 at least. In the last five minutes we let it slip.
"The crowd got behind them, they got a head of steam up, worked hard and got their goals. But we should have got other goals earlier on.
"But it is over now. We just need to prepare. We should have wrapped it up. But that is the way football is. It can be a harsh game.
"We can't afford to switch off against Barcelona. We need to work hard for the 90 minutes, or 94 minutes if there is added time, and see what happens."
Despite being unimpressed with his own display, Watt picked up the man-of-the-match award against United and is hoping he will be involved against Barcelona.
He added: "I don't think I did as well as I could have. Okay, I got an assist and the goal, but my all-round play wasn't the best. I know I can do better than that.
"You can score two or three goals and you are still not playing well. Hopefully that is my bad game out of the way and I can do better in the next one.
"I will just need to see what happens in midweek. Hopefully I will be on the bench or starting."