Watkins and John McGinn struck for the 2-0 win at Villa Park as they, sitting in fourth, went five points clear of fifth place on the Premier League table.
England striker Watkins said afterwards: "Massive for us with it being the last game going into the international break and all the teams around us playing before and them dropping points.
"We knew the job in hand and we have taken it and maximised our opportunity to try and get into the Champions League places."
On his goal, he continued: " It was sweet because I had quite a few opportunities. The ball just fell to me nicely and I have done well to lift it over the keeper.
"We are happy with that off the back of a bit of poor form. It is one of the best performances we have had this season."
On missing out on the England squad, Watkins added: "Everyone wants to play for their country but I expected that ebcause my form has not been that great. I know what I can do and when I put on an England shirt I feel like I have always performed well."