Defoe, 25, did not even make the bench in two of Spurs' recent away games, at Bolton and Newcastle. And he got on for only the final half-hour against Blackpool.
But Ramos said: "I always say the players pick and drop themselves with their behaviour and their efforts.
"If Defoe shows me he deserves time on the pitch, he will get it.
"If not I will start with somebody else because what we managers want is that the team works well and players who work for the team will be in the team."