The Netherlands legend will replace Dick Advocaat at Alkmaar at the end of the Eredivisie season after agreeing a two-year contract.
Van Basten's immediate loyalties lie with Heerenveen, though, and he has been put in the difficult situation of coming up against the club that he will take charge of when the Europa League play-offs finish.
Heerenveen are riding on the crest of a wave heading into Wednesday's semi-final first leg, having secured fifth spot in the Eredivisie after reeling off four consecutive victories - conceding just one goal in the process - and they have only been beaten once in their last 10 matches.
Former Milan striker Van Basten was unable to guide the club into the Europe last season, as they were beaten in the semi-final by Utrecht - who went on to win the final - after finishing eighth.
Heerenveen missed out on fourth as PSV beat NAC Breda in the final round of matches on Saturday, but will be buoyed by a fine run of form and face an AZ side who finished 10 points behind them in eighth spot.
While Heerenveen come into the first leg at AFAS Stadion full of confidence, AZ are without a win in eight games in all competitions and Advocaat will be hoping the tide will turn when it matters most.
Former Netherlands coach Advocaat decided to step down at the end of the current campaign, having only been appointed in October, and the 66-year-old will be eager to sign off in style.
AZ's poor run of form included a KNVB Cup semi-final defeat to Ajax and a Europa League quarter-final exit at the hands of Benfica, so their supporters will feel they have had more than enough cup disappointment this season.
Groningen and Vitesse will contest the other semi-final and both sides also come into Wednesday's first leg at Euroborg having experienced differing fortunes at the end of the season.
Erwin van de Looi's Groningen side recorded six wins in a row to take seventh, a run that ironically started with a 3-1 win over Vitesse.
Groningen forward Richairo Zivkovic has scored five goals in his last seven games and will be eager to continue that streak as his side look to go one better than last season, when they were also beaten at this stage by Twente.
Vitesse are attempting to secure a Europa League spot for the third consecutive season, but they are without a win in their last seven games and lost 2-1 at Utrecht on Sunday.
The return leg of the semi-finals take place on Saturday, with a two-legged final to follow.
