The Hornets beat Reading 1-0 thanks to a second-half strike from Almen Abdi, despite having Gabriele Angella sent off.
And Watford boss Slavisa Jokanovic was delighted with his side's performance - but only after the break.
"It was a very important win for us. I was very proud of the team, especially in those last 15 minutes. I wasn't so happy with the first 45 minutes," Jokanovic told BBC Sport after the win.
"We did not start very well, Reading were stronger than us and we made unnecessary mistakes. But we had a big reaction in the second half. We worked hard together as a team, scored the goal and kept the clean sheet.
"It is very important to win these type of games, it will give us great confidence."
Ighalo, who replaced Deeney with minutes to go, also took to social media following the close win.
Great Win lads,the fans were amazing— JUDE (@ighalojude) December 20, 2014
Very good result today performance wasn't great but 3 points and 3 back to back wins is a massive step forward have a good weekend— Troy Deeney (@T_Deeney) December 20, 2014
Also massive well done to @Pupik33 for clocking up 100 appearances for Watford solid as always bro— Troy Deeney (@T_Deeney) December 20, 2014