The pair of them have been inseparable for months, playing 31 consecutive games as the twin pillars of the Celtic defence. But it would not matter how long he spent searching, Ambrose would never find van Dijk's name on the latest list of players selected to play for the Netherlands.
There were 33 of them in total, including 10 defenders. Manager Louis van Gaal has selected his men for a friendly against France but it looked a lot like a provisional list for the World Cup finals in Brazil. Van Dijk must hope that his manager's mind remains open to persuasion, because his omission suggests he is no closer to securing a seat on the flight to South America.
Even allowing for the prejudice of being impressed by familiar players who are seen regularly impressing in Scotland, and accepting a level of ignorance about the form and abilities of the others who have been chosen instead of him, it is still difficult to believe that his country can be so well endowed with centre-halves that Van Dijk could not be very close to selection.
"For the way he's playing I think it is unimaginable that he could not make a squad of that number of players," said Ambrose yesterday. "I would be disappointed if Virgil isn't at the World Cup. I think he should be there because he's a great player. I am certain that Holland really need the talent he's got. He has every quality to play in the World Cup. I have seen Holland play and I think he still has a chance, but it is up to their manager.
"He has to decide what kind of players fit into his squad the best. But I believe that everything is possible in football and that before the World Cup Virgil can play for Holland. Virgil will have a long time in the game and will play for Holland. He is still young and will work even harder."
The omission of Van Dijk, as well as the ongoing doubt over Fraser Forster's place in the England squad, inevitably has led to some suspicion that simply earning a living in the SPFL Premiership counts against players who are candidates for the leading international nations.
Fitness permitting, Ambrose is certain to be at the World Cup for Nigeria. Neither his current manager Stephen Keshi nor the previous handful to have picked him since 2008 were too fussy about where he played his club football.
"I was never told that playing in Scotland would be bad for my Nigeria chances [he signed from the Israeli club Ashdod in 2012]," said Ambrose. "The first time I played for my national team I was playing in Nigeria. And when I played at the Olympics I was playing in the second league, not the Premier League. So it doesn't matter where you play, it matters who the player is.
"I believe Fraser is different class. With Celtic he has done everything.
"He has kept clean sheets and in every game he's played he has been in top shape. Week in, week out he's been doing it. He should be given a chance to play in the World Cup because I don't think there is much difference between playing in Scotland and the English Premier League. We have played against the best in the Champions League and Fraser has kept Celtic going.
"He should go to the World Cup and it doesn't matter if he's playing in England, Scotland or Germany. What he is doing is special."
The World Cup was on Ambrose's mind yesterday as he is one of the Celtic players hearing to the tournament who has backed an initiative called Project Fair Play, which will send thousands of football shirts to disadvantaged children in Brazil. Supporters are being asked to dig out their unwanted football shirts, especially children's ones, to donate. Celtic have contributed 1000 shirts to the project. "When I was a kid I used to support Brazil because of the way they played football. I didn't have the kit because I always wanted to get a real one! I hope I will if we play them in the World Cup."
Ambrose helped Nigeria to their fifth World Cup finals in six qualification campaigns. They are in what has the look of a kind group with Argentina, Bosnia-Herzegovina and Iran. "I should be excited about Brazil but I'm not. Not yet. There are three or four months to go and to work on and right now I am only thinking about Celtic."
It is on SPFL Premiership duty that Ambrose will tomorrow return to Tynecastle, the scene of arguably Celtic's most persuasive display of the season when they routed Hearts 7-0 in the Scottish Cup in December.
Ambrose suggested even that display could be improved upon.
"This time it is going to be a different ball game because we know this time they are going to give us a good fight after what happened the last time. They won't want that to repeat itself. At the same time we want to do maybe more than what we did the last time. So it is going to be a two-way fight. But we are Celtic and we know how to win games."
n Anyone wishing to support the Project Fair Play campaign can drop off football shirts at one of over 200 collection points across the UK. To find the nearest, visit www.projectfairplay.org.uk. Shirts can be dropped off from March 1 until April 15.