Liverpool boss Jurgen Klopp saw his side denied three points on the opening day after Miguel Britos' injury time equaliser shared the spoils in an entertaining 3-3 draw at Vicarage Road.
The Hornets lead twice through Stefano Okaka and Abdoulaye Doucoure, either side of a splendid Sadio Mane goal after 29 minutes. Roberto Firmino levelled matters from the spot after half-time before Mohamed Salah got a debut goal his performance deserved.
Speaking to Liverpool's official website after the dramatic draw, Klopp said: "You have to fight for a result, you have to use the things you create and you have to accept a few things for this day, but to use it for the next game and try to work on it.
"Everything is different in a league game than a pre-season game. I was not happy in the first half with the situation; it was very physical and Watford were too often the winners in these situations.
"They didn’t create too much with it, but scored two goals. The first one, in our specific situation everyone will say it was clear because it was a set-piece, but it was a good cross and a good run. One of [our players] didn’t close the gap so he could not run.
"We have to work on it, no doubt. The second goal was unlucky and a formation problem. Alberto lost the challenge, which can happen obviously – maybe it was a foul or not, I’m not sure – there was a gap open, they played a pass and I thought it was offside, I’m not sure if it was. They passed the ball in our box, we defended the first time but then struck the ball against our own legs so that makes it a little bit unlucky.
"We had more chances, especially after set-pieces, with very good crosses, good headers and they were lucky in these situations and we were extremely unlucky. Then we scored two wonderful goals in the second half, it was really good, we had our moments and then we conceded an offside goal.
"That’s really not fun, it’s difficult to accept. It feels not too good, but we know we can do better and have to do better – that’s what I told the boys."