Watford dropped into the Premier League relegation zone on Tuesday and interim head coach Hayden Mullins does not expect to receive any favours from Arsenal on the final day.
The Hornets 4-0 loss at home to Manchester City dented their survival hopes before Aston Villa's victory over the Gunners later saw the Vicarage Road club fall into the bottom three for the first time since February.
An intriguing backdrop to Sunday's fixture at the Emirates will be Troy Deeney's comments about the north London club back in October 2017.
"Going back to us as a squad and what we need to do, we know what we need to do. It is about focusing on us, getting together as a squad and seeing what the next few days bring."
Foster told Sky Sports: "We have to look at ourselves. We've got a massive game on Sunday and that's all we've got to look at now."
Sterling's brace took his tally for the season to 29, with 19 in the top flight.
He took over spot-kick duties from Kevin De Bruyne at Vicarage Road and although his shot was saved, the attacker tapped home the rebound but was unable to complete a hat-trick before he was withdrawn in the 64th minutes.
"It's massive as a winger to score 20 goals in the Premier League," Sterling told mancity.com. "We have one more game left, so I hope I can do it then.
"I scored the first one and I knew I was on 18 so I stepped up (for the penalty). I knew I had another chance to get the hat-trick, it didn't happen but I'm really happy with the two goals."
