IT is, so the theory goes, the most important relationship in football.

Successful chairmen and managers are often said to be as close as family, but in Dinamo Zagreb's case it really is a band of brothers. While the hugely controversial, maverick figure of Zdravko Mamic is the club's executive chairman, younger sibling Zoran serves as both head coach and sporting director.

While the younger Mamic brother made the greater strides in the game, spending most of his career in the Bundesliga and being part of a Bayer Leverkusen squad which once travelled to Ibrox on Champions League duty, Zdravko has a flair for chaos. In no particular order, he is alleged to have admitted match fixing on numerous occasions, has been known to celebrate victories with Nazi salutes and traded blows in the director's box with a high-profile representative of Hajduk Split after a victory in Croatia's Eternal derby in March.

Whatever the rights and wrongs of the brothers' control of the club, theirs is a formidable familial stranglehold from which plenty seem to profit. Fans of the club, including notorious ultra group the Bad Blue Boys, can hardly quibble too much considering the club has recorded nine Croatian top division titles in a row, but charges of nepotism and conflict of interest have rarely been far away.

As a non-profit members club, Dinamo Zagreb benefits from tax exemptions, regardless of the millions in transfer revenue which has come into the club in recent seasons. Consequently, these days they are a rich club, capable of attracting one of the world's top young strikers, Angelo Henriquez of Chile and Manchester United, on loan. It is thought that the club are optimistic of persuading him to stay longer.

The bedrock of this financial successes is efficiency at developing young talent, something else Celtic could be envious of. A recent Croatia international squad contained just one man, Ivan Rakitic, now of Barcelona, who hadn't been present at some stage or other in Dinamo's academy.

In the past seven years alone, combined proceeds from the the sale of Luka Modric to Tottenham, Vedran Corluka to Manchester City, Eduardo to Arsenal, Dejan Lovren to Lyon, Mario Mandzukic to Wolfsburg, and young firebrand Mateo Kovacic to Inter Milan are touching 70m Euros. Zdravko, it has been claimed, personally profited from many of these deals by helping to broker them as an agent.

Making money is one thing, however, making a mark in European competition is something else entirely. It is to the club's shame that 44 years have elapsed since they were last in continental competition beyond the New Year, and the 2014/15 season has been pencilled in as the time to bring that ignominious record to an end. While the Champions League was the real target, the Europa League offers opportunities for Zagreb to make their mark on the international stage, and their 5-1 victory against Romanian outfit Astra Giurgiu in the opening match day was a statement of intent, particularly from star striker Hilel Soudani, who scored a fine first-half hat-trick. The Algerian World Cup squad member - his international manager is former Zagreb boss Vahid Halihodzic - agreed a new deal to stay at the club early in the season and has been playing like a world-beater ever since.

Celtic boss Ronny Deila for one regards him as the biggest threat they will face on Thursday night at Celtic Park. "We've seen their first game against Astra and we saw them again on Saturday at Slaven Koprivnica," said Deila. "Soudani, who plays up front or coming in from the right, is very strong. Zagreb are known for developing good young players and they've sold a lot of good players to big clubs around Europe. Teams from the Balkans are always very good tactically - they do what they need to do to win games and I expect Zagreb to be the same. But they also have good attacking strength and like to play football."

Lending this experience at the back is 36-year-old skipper Josip Simunic, a veteran of five major tournaments with Croatia, who himself is no stranger to controversy. After a lengthy legal wrangle, he is currently serving an international ban for leading Croatian's fans in an alleged neo-Nazi chant after a 2-0 win against Iceland in November 2013. Deila, who was impressed with Astra when his Stromsgodset side met them in a friendly last season, prefers to stress the merits of the Croatian side's performance rather than the demerits of the Romanian side.

However, having been present at Celtic's match against Barcelona match during last year's Champions League, he is determined to re-establish the fear factor at Parkhead after that tame defeat to Maribor in the final qualifying round of the this year's edition of Europe's major competition. Croatian sides have a reputation for not travelling well and at least some of the statistics do actually bear that out: not only have the Croatian national team never won in Scotland, Dinamo have lost all three of their previous matches in Scotland without scoring, while Celtic have won both of their previous meetings with Dinamo without conceding. These were a 3-0 win in the European Cup Winners' Cup in 1963, and a 1-0 win for Jozef Venglos' side against a Dinamo side in a Champions League qualifier in 1998 which introduced a young Mark Viduka. However, Dinamo have won all three of their European away matches this season, while Celtic have won three of their last six at home.

"Zagreb played a good game but it's hard for me to say what level Astra are at," said Deila. "They scored with every chance they had in the first half, and when it's 3-0 it's tough for the other team. I think the four teams in our group are quite equal and it's up to us to use our home advantage. Celtic have been fantastic at home in Europe for many years. We've had a good away game and we're looking forward to a good game at home now. We're going the right way - we look like a team now and I enjoy that."