What turned out to be the only goal of the match came in first-half stoppage time.
The victory strengthened Liverpool's hold on third place with 69 points, three points clear of fourth-placed Manchester City and four ahead of Manchester United, who are fifth.
"We scored a fantastic goal", he said. I couldn't do anything else there, because the ball was a little bit behind and I couldn't head it. We could have done better, of course.
The German revealed that match-winner Can had been playing with a slight calf issue when he scored a jaw dropping bicycle kick on the stroke of half-time, but expects that this showing will silence some of the midfielder's critics.
"We thought we needed him and he tried as good as possible. Sometimes it was not as good as it could have been, but meanwhile these problems are sorted and now he can build on his performances". We won, it was very important.
"We have the opportunity to fight for it". We want to stay focused. I think we've shown we have learned a lot.
"In the end, you get what you deserve".
'I didn't think too much, to be honest, ' he added. "If people think we have the three points against Southampton (next weekend) they cannot have seen Southampton this season". It was a hard game to play, we started well but then we had to change Coutinho, Adam Lallana only trained twice in the last four weeks so it wasn't ideal but we were patient and tried to create moments.
"Everything is in our hands".
However, Can might not be at the club to play in next season's Champions League as his current deal is set to expire in 2018 and talks over a new contract have stalled.
Liverpool were denied a second late on when Watford goalkeeper Heurelho Gomes thwarted Daniel Sturridge, while a last-gasp volley from Watford's Sebastian Prodl crashed against the visitors' crossbar.
Walter Mazzarri's side remain on 40 points in the table, eight points clear of the bottom three, and the Italian pointed a finger at the officials as his side slipped to defeat.
"It is a different game to Liverpool, it is away from home, but I think we can", he told reporters. "In the first half aside from another great shot from Lallana we didn't concede anything to them". Usually I don't like to speak about luck but today we were completely unlucky.
He said: "It feels really good as you can imagine".
His 10 goals in the league this season are just three behind top-scorer Mane, while his six assists are only one fewer than Lallana, the side's most creative asset this term.