The Hornets have endured a tumultuous start to the campaign and currently sit bottom of the table with just two points from five games.
Their poor start prompted the board to act during the international break, sacking Javi Gracia and turning to a familiar face as his replacement.
Fellow Spaniard Quique Sanchez Flores was previously in charge during the 2015-16 season, playing a significant role in establishing the club after their promotion from the Championship the previous season.
A 13th-place finish and an FA Cup semi-final appearance proved a decent return before leaving after failing to agree on a new contract.
Sanchez had been giving out positive messages during the build-up to his first game back in charge against Arsenal on Sunday and the early signs were good.
A fast start at Vicarage Road got the fans on side but their momentum was halted as Pierre-Emerick Aubameyang grabbed a first half brace.
The Hornets returned from the break with renewed vigour and salvaged a 2-2 draw through Tom Cleverley and a Roberto Pereyra penalty.
Sanchez was understandably pleased with the spirit his side showed and Foster believes their improved performance shows a first win is around the corner for his side.
"To draw the game 2-2, it's great to get a point but three points were there for the taking," he told the club's website.
"But you can't take it away from the lads, they were fantastic today, in the second-half especially. We created so many chances, the win's going to come soon."
Watford's next outing sees them travel to the Etihad to take on Manchester City on Saturday.
They then face Swansea in the EFL Cup before visiting Wolves and hosting Sheffield United ahead of the October international break.