The Tykes were rewarded for a 3-2 second-round win over Burnley with a home tie against Robins' former club next Tuesday but he insists nobody at Oakwell is looking beyond Saturday's home league clash against Bristol City.
Robins said: "Nobody here is thinking about the Manchester United game. That's an extra one next week but this match on Saturday is our bread and butter and that's our only focus.
"Saturday is more important for us because it's the next game. There's no point thinking about anything else."
Robins launched his playing career with United in 1986 and spent six seasons at Old Trafford before moving on to Norwich for a fee of £800,000.