"If you're not positive [about Can] after this game, this goal, then something is wrong!" said Klopp.
"I have never scored a goal like that - maybe when I was younger".
He said: "Aside from the crossbar from Prodl, there were two mistakes from the referee, offsides against (Stefano) Okaka and (Troy) Deeney, so I think we played a good game".
'I didn't think too much, to be honest, ' he added.
The Manchester clubs and Arsenal all dropped points on Sunday and Liverpool knew they could grab the initiative in the race for Champions league places.
A lack of midfield creativity and incisive passing from deep meant it was a pretty comfortable half for the Hornets, but Can's stunning strike changed the dimension of the game and gave Liverpool something to hang onto.
"Everything is in our hands".
"We played against a good team who are third in the league and we did OK". We had a lot of talks about this, and everybody saw the performances and thought "What's wrong with him?' We thought we needed him in these moments and he said 'OK, I'll try".
The Reds moved four points clear of fifth-placed United, though they have played an extra game.
Liverpool's hopes of securing a top-four Premier League finish were already dealt a major blow with Sadio Mane out for the remainder of the season, and losing Coutinho to injury may have been the hammer blow manager Jurgen Klopp could have done without.
Liverpool have also been boosted by confirmation that Philippe Coutinho, taken off after just 13 minutes with a dead leg, is not likely to miss the run-in.
"In the end, you get what you deserve".
The Brazilian has started to rediscover his form over the past few weeks having struggled to settle back into a rhythm following his recovery from a separate ankle issue earlier in the year.
"We defended well I think".
"Everybody wants it so much and we're going to keep fighting for it". Find us on Facebook too! Sometimes when you get these knees to the side you can't run them off. A bit exhausted at the end but I've had fix or six weeks out of the game so that's only normal.
"But they scored a goal like this and we could have scored with Prodl, but it didn't happen".