The Australian yesterday received his work permit for the UK having joined United earlier last month.
He missed out on United’s 1-0 victory over AZ at Tannadice last Thursday but could be in line to start in the Netherlands in the return fixture.
The left-back has over 50 caps for his country and is set to be part of the Australia squad that travels to the World Cup in Qatar later this year.
Although he is yet to play a competitive fixture this season, Ross is confident that Behich will be able to handle the rigours of Europa Conference League action on what could be a momentous night for the Tannadice club.
He said: “When you have someone with Aziz’s experience it negates any worries about handling the occasion because he’s played in Europe numerous times and has a lot of caps for his country.
“He’s played in a lot of big matches in his career and has that pedigree.
“Aziz is tough, he’s robust and naturally in a good condition so there’s that psychology aspect of it as well, knowing he can get through games.
“If we didn’t think he was ready to go he wouldn’t have travelled, no matter the work permit situation.
“It has been frustrating for both us and Aziz because it has taken a long time.
“He’s a passionate lad and you could see him get increasingly frustrated because he’s been preparing to be involved right to the last minute.
“So when we contacted him to say it was all done, he was very happy.
“He’s been desperate to get going. In some ways watching last week’s game and the two league games have made him desperate to get going more.
“He has trained really well and has been desperate to be involved, so we are really pleased to have him with us.”
Despite United’s 1-0 lead, AZ are favourites to progress to the play-off round where either Riga or Gil Vicente lie in wait.
Ross said: “AZ are favourites for the match and the tie overall.
“Given their record in Europe and their record here in their home stadium they have to be.”