The Tangerines travel to the Netherlands with a one goal lead following last Thursday’s thrilling victory over the Dutch side at Tannadice.
McGrath, 25, got the assist for Glenn Middleton’s winner on what was his debut for the club, having arrived on loan from Wigan Athletic last Wednesday.
It was the Irishman’s 15th appearance in European competition stretching back to 2015.
The midfielder was not short of suitors before joining United, with Aberdeen also interested in him, but it was the Tayside club who did the most get a deal done.
The opportunity to again test himself against foreign opposition was a key factor in him deciding to move to United.
McGrath said: “These big European nights are something I missed. I had a few of them with Dundalk and, when you look back at the memorable games, those are the ones you reflect on. Last week was one of the best, result-wise and in terms of the atmosphere. But we’re only halfway there and can’t get carried away.
“It’ll be a different challenge in the Netherlands – we know that- but we’ll take so much confidence from the game at Tannadice.
“I think back to Slovan Bratislava [a Europa League qualifying defeat in 2019] and beating Riga on penalties [in the first round of Champions League qualifying in 2019] – I’ll never forget the scenes out in Latvia – and I hope there’s another really big night to come."
Aberdeen chairman Dave Cormack hinted on Twitter that the financial package proposed by Wigan was not good value and that the club pulled out of the deal. However, McGrath insisted that United were the only club that he wanted to sign for.
“I didn’t see those [comments by Cormack],” McGrath added. “I had a few options, not only in Scotland but down south and abroad as well. It was about weighing everything up and, after seeing everything that was going on at the club, and the feeling around the place, this is the only place I wanted to be.”