City need a point at Vicarage Road to guarantee their place in next season's Champions League, while victory would wrap up third place and a direct passage into the group stages.
It will be the final game before an expected overhaul of the squad during the summer, but Guardiola insists that he is looking no further than Sunday.
"We still have 95-96 minutes to fight to do one thing so important for the club. It is a crucial game for us, absolutely a final," he told reporters.
"It is in our hands. Just look what we have to do - win the game. We travel to London for that. Every game is a pressure, every game we play for everything.
"I spoke three days ago about the future. I'm not going to speak today. I know the question is going to come but forget about it. The day after tomorrow we have a real final. We have to focus on that. I will talk in the present.
"We didn't fight until the end because two teams were better. We dropped too many points at home. We will have to improve that. We have to work harder next season to reduce the gap."
Victory for City would see them make it four league wins in a row for the first time since the beginning of March.