Rangel and Davies flanked the Swansea back line for two seasons, before the latter departed for White Hart Lane in a close-season deal that saw Michel Vorm make the same switch and Gylfi Sigurdsson move the other way.
The Wales international initially struggled to break into the Tottenham team, but has now started five matches on the bounce in all competitions.
And Rangel says niceties will have to be put to one side when Davies returns to the Liberty Stadium at the weekend.
"Obviously Ben is a great player and a great professional," he told the South Wales Evening Post. "He's been doing well, but we're not friends on the pitch, we know that.
"We are professional and we have to compete and win the points. Afterwards we can talk and be friends again.
"I'm glad he's doing well, but if I'm in the starting 11 I will be happy to play against him and stop him."
Swansea are sweating on the availability of Lukasz Fabianski after the goalkeeper was sent off following a collision with Diafra Sakho in a 3-1 defeat at West Ham on Sunday.
The Welsh club have since appealed the red card, and Rangel backs that stance.
"I don't agree with the sending off," he added. "It could be a red, but the ball was going wide.
"Fabs has come out and there was contact. It was a foul, but if he gives a yellow I don't think there's a problem."
