In-form Oxford sit eighth in the third tier ahead of Wednesday evening's sold-out cup tie following just one defeat in 19 games in all competitions.

Robinson wants to make the city proud against Pep Guardiola's side but cannot help having one eye on the weekend.

Asked if defeating City would be a greater achievement than beating Van Gaal's Red Devils, he told the PA news agency: "Yeah – only if we win on Saturday as well though.

"It was a very memorable evening (against United) but every game has its different challenges and, let me assure you, this is much more of a difficult challenge.

"We were lucky at certain stages to stay in the game, took our chances when they came along and we exploited the opposition in the right areas when we needed to.

"We don't prioritise any game, we just want to win every game we go into but I think the most important thing is we respect the game that we have at the weekend."

City travel to the Kassam Stadium as holders but a staggering 14 points behind leaders Liverpool in their faltering title defence.

However, they provided an emphatic display of their ruthless brilliance by dismantling Arsenal inside 45 minutes on Sunday.

Robinson was not at the Emirates Stadium to watch that Kevin De Bruyne-inspired 3-0 victory but needs little reminder of the task facing his team.

"It's a massive challenge because you are coming up against one of the greatest teams in the land and arguably the greatest team in the world, or one of them, with the best manager over the last 15 years, so it's going to be a very, very difficult ask for us," he said.

"But it's one we want to embrace and try and enjoy and hopefully give Oxford something to be proud of.

"On any given day these are fantastic, these are some of the best players in the world so you've just got to make sure you do your job correctly."

Oxford, who lost 3-0 at home to City in the third round of the competition last season, have been plagued by injuries in recent weeks and have a lengthy list of absentees.

The U's last reached the League Cup semi-finals during the 1987-88 campaign, two seasons after lifting the trophy under Maurice Evans with a 3-0 Wembley victory over a QPR side managed by former boss Jim Smith.

Smith, who guided Oxford to the top flight for the first time in the club's history with successive promotions in 1984 and 1985, died last week aged 79 and will be remembered with a minute's applause ahead of kick-off.

On what promises to be an emotional occasion for his club, current manager Robinson is looking forward to testing himself against former Barcelona and Bayern Munich boss Guardiola for the second successive season.

"There is tremendous respect for him in the industry," he said of the Spaniard.

"Being a young, British manager, he's someone that you do look up to and someone that you can't help but have tremendous respect for.

"We just hope that we can do our job right on the day and make sure that we achieve what we want to achieve and that's putting a hundred per cent effort into the game.

"If we can do that, we'll be in a better place."