That is the view of Arsenal legend Martin Keown.
United’s Argentinian centre-half and Chelsea’s Brazilian-born striker clashed when the two went head-to-head last month.
The Blues came out on top in the 1-0 FA Cup quarter-final triumph at Stamford Bridge.
But player-turned-pundit Keown, who had plenty of heated incidents throughout his own career, believes Rojo and Costa will continue where they left off.
The battle between Marcos Rojo and Diego Costa proved intriguing last time Man Utd and Chelsea met
The United defender did not take any nonsense from Costa when the sides met in the FA Cup
However, the Manchester United centre-half, along with partner Eric Bailly, must stay alerted to the dangers Chelsea pose.
“It promises to be an explosive battle between Diego Costa and Marcos Rojo,” Keown told the Daily Mail.
“The United defender did not take any nonsense from Costa when the sides met in the FA Cup and there could be lots of fireworks on Sunday.
“Costa will be scratching his head as to why he has not been shortlisted for the PFA Player of the Year award.
Manchester United v Chelsea combined XI Wed, April 12, 2017
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Martin Keown's warned Marcos Rojo he must have total concentration when going up against Diego Costa
“Rojo and Eric Bailly will need to have the games of their lives to stop him.”
Keown predicts Chelsea to prevail 2-1 winners at Old Trafford tomorrow (4pm), where a win would edge them ever-closer the title.
But United’s quest for Champions League qualification, along with stopping Diego Costa, is more than enough motivation for Rojo & Co.