Dutch champions Ajax host APOEL in what will be both teams' final Champions League fixture of this season, with the sides battling it out for third spot and a place in European club football's secondary competition.
Paris Saint-Germain and Barcelona have coasted through Group F, with their meeting at Camp Nou this week set to decide who wins the pool.
But while the Champions League last 16 is out of reach for Ajax, coach De Boer is determined for his side - who sit one point above APOEL - to avoid defeat and claim the secondary prize of a spot in the Europa League.
De Boer watched his team dismantle Willem II 5-0 in the Eredivisie on Saturday, and is thrilled to be heading into this week's clash with the Cypriot champions on a high.
"The way we won [against Willem II] will go with us on Wednesday," said the Dutchman.
"The duel against APOEL is very important for us."
One man Ajax will have to do without on Wednesday, though, is striker Kolbeinn Sigthorsson.
The Iceland forward opened the scoring early on against Willem II, but had to be withdrawn shortly after due to an injury and will be sidelined until after the mid-season break, Ajax confirmed on Monday.
"Kolbeinn will probably be out for a couple of weeks - it seems to concern a muscle between his shin and ankle," De Boer added.
"It's not a serious injury, but it's possible to miss three weeks because of it."
El Ghazi missed Saturday's match, but De Boer confirmed afterwards that the teenager - scorer of six goals this season - will be available in midweek.
Giorgios Donis' side travel to Amsterdam in the knowledge that only three points will be enough to continue their continental adventure this term.
After being outclassed by Barca in a 4-0 home defeat in their last Champions League outing, APOEL have claimed successive 1-0 wins in the 1. Division and sit five points clear of Apollon at the top of their domestic table.
