Star striker Sergio van Dijk and left-back Cassio will return to Adelaide United's line-up for tonight's knockout final with Wellington Phoenix.

van Dijk, the A-League's leading scorer this season, and Cassio both missed the final regular season match against the Melbourne Victory whilst due to injury but will boost the Reds line-up for the Hindmarsh Stadium encounter.

"Cassio is good and Sergio (van Dijk), we knew there would be no problem if we just give him a couple of days off, so they are 100 per cent fit and available," said coach Rini Coolen.

Coolen was also buoyed by the fitness of Dutch winger Andy Slory who should be able to make an impact at some stage of the game after coming off prior to half-time against the Victory.

"We know he can't play 90 minutes but he can play a longer period (than last week) so that's fantastic, his injury is not a problem," Coolen added.