Gianfranco Zola insists there is still plenty of room for improvement from his side despite a comfortable 2-0 victory over Birmingham.
The Hornets raced into the lead through Almen Abdi's third-minute penalty and then fellow Udinese loanee Matej Vydra's second goal of the season after 17 minutes put Zola's team firmly in control.
"I was really pleased with the performance. We scored two goals, created plenty of opportunities and played plenty of good football," said Zola.
"It is a pity we couldn't keep the same rhythm in the second half and we conceded too much space to Birmingham, but that is understandable because Birmingham are a very good team.
"It is something for us to build towards in the future because once our physical condition is better then we will be able to perform like that for longer than 45 minutes."
Watford kept possession excellently in the first half and created a number of good chances. After the break Birmingham enjoyed more of the ball but still failed to trouble Manuel Almunia in the Watford goal.
Birmingham boss Lee Clark was very disappointed with his side's performance but was quick to praise Watford.
"If you go 2-0 down then it is very tough to come back and we found that on Tuesday night when we were in the same position," said Clark.
"Watford were excellent and I wouldn't take anything away from their performance, but we have given them two very poor goals.
"In general, it was a very poor performance in the first half. We were not good enough in the first half but it is a tough one because I know there is so much more in that dressing room."