The Dutch side travel to Pittodrie for the first leg.
Or most of them will, at least. Groningen played in a pre-season friendly match with German side Oldenburg at the weekend, with both of the players signed during the close season succumbing to groin injuries. The match was watched by Aberdeen scouts.
"There is no point taking any risks at this stage of the season," said Van de Looi. "We will assess them before we travel, but they are both unlikely to play in Scotland. We know that we face a very tough game."