"I know a little about them because a good friend of mine who works in the game saw them at Chelsea and he said they look strong," said the midfielder. "It was difficult for Chelsea to beat them.
"We have to be ready for a battle and to be at our best, to be strong, together, run, tackle and work for each other."
Meanwhile, Gus admitted the lads would have loved to have kicked straight back into action after a fine win against Everton last time out.
Unfortunately that 3-0 win, with Gus on target, was followed by an international break.
"It is typical," signed Gus. "It is the same everywhere in the Premiership because of internationals but when we were playing badly we couldn't have a break, we then have three games in a row quite good and we have to have a break!
"We have to be ready for this game though. It is important because we then have three home games."
Gus Poyet has had a little inside information on Leicester City and knows to expect a tough test on Sunday.