He worked with a number of players who have since turned professional and received International honours: Wayne Routledge, Gary Borrowdale, Ben Watson, Tom Soares, Sam Togwell, Lewis Grabban, Rhoys Wiggins, Andrew Julius, David Hunt, Gavin Heeroo, Teerathep Winothai, Will Antwi and Craig Dobson. At the start of 2003, he was appointed First Team Coach at Argeş Piteşti, working with players such as Nicolae Dică, Andrei Prepeliţă, Raul Marincău, Marius Bilaşco, and Adrian Iordache. His progress at Argeş Piteşti brought him to the attention of Romanian Serie B club, Cimentul Fieni. He was appointed Caretaker Manager of the club, towards the end of 2003. In a limited time, and with scarce playing and financial resources, he managed to save Fieni from relegation and help restore pride to the team. In recent years he has been a member of the Technical Support Staff of the Romanian Football Federation. His coaching and Coach-Educator expertise have been used to help develop their UEFA-A and UEFA-B licence coaching courses. He has also consulted on player development programmes for the U16 through U21 teams. He co-ordinated the 2006 visit to Romania of Howard Wilkinson. The former Technical Director of The Football Association was brought over by Marinica to conduct a session of the Romanian Football Federation's UEFA Pro Licence course. "I have known Mario for a long time. He is an intellectual coach; methodical, a statistician, and an excellent personality." Mircea Rădulescu, Technical Director of the Romanian Football Federation. He has been employed by Hertha Berlin, Watford FC, Stockport County FC and Notts County FC for scouting and technical analysis of forthcoming adversaries. He has also been employed to assist Romanian clubs Steaua București and Dinamo București in preparation to face English opposition in European competition. His unsurpassed tactical analysis provided the basis for Steaua București's defeat of Middlesbrough FC and Dinamo București's 5–1 defeat of Everton F.C. in the UEFA Cup. It was the first time Everton F.C. had conceded five goals in European competition. During the 2006 FIFA World Cup, he assisted the Paraguay national football team, providing technical analysis of their group B rivals: England, Sweden and Trinidad & Tobago. From 2005 to 2007, he completed the UEFA Pro Licence with the Irish Football Association, graduating alongside him were Chris Coleman, Jim Gannon and Bernard McNally; amongst others. In the 2008–9 season, he was the interim manager of Romanian Liga I (Premier Division)