A government-funded £25 million upgrade to Windsor Park could unfairly extend the dominance of Northern Ireland's most financially powerful football club, the High Court heard today.
Linfield's domestic rivals and even opponents in cross-border competitions would be disadvantaged by redeveloping the national stadium it owns, a judge was told.
Another Irish League side, Crusaders, is seeking to block the proposed scheme, claiming it amounts to unlawful state aid.
But lawyers for both the Department of Culture, Arts and Leisure and Irish Football Association argued the challenge is premature and should be kicked out.
Mr Justice Treacy will rule on Wednesday on whether the case can proceed.
The Windsor Park redevelopment is part of a plan that also includes the Ulster rugby ground at Ravenhill and the GAA's Casement Park
A total of £110m has been set aside for the three building projects through the Department.
According to Crusaders the upgrade breaches European Union competition laws.
The club claims funding the Windsor Park project is a clear example of state aid for two private entities - the IFA and Linfield.
It argues the proposals would create unfair revenue streams as well as superior facilities at the south Belfast ground.
Applying for leave to seek a judicial review, Crusaders barrister Peter Girvan told the court: "Linfield have significant market power already, if not a dominant position.
"Linfield are the most successful club in terms of cups and league championships.
"Is there an effect on the competition? We say yes, there's a competitive disadvantage to Linfield's direct competitors in Northern Ireland.
"It also places clubs Linfield competes against in the Republic of Ireland at a disadvantage."
The court heard how the IFA has negotiated a new deal to lease the stadium for international matches.
But Paul McLaughlin, for the Department, insisted no final commitment has been given to provide the £25m earmarked in the Stormont Executive's Programme for Government.
He acknowledged the process was at an advanced stage, but outlined how the stadium funding depended on agreement on a range of sporting and social integration projects.
"The exact scope of some of the programmes the IFA would have to deliver are not finalised. That's why we say the matter is premature," Mr McLaughlin said.
Although he rejected the state aid claims, the barrister also outlined an intention to seek the European Commission's view on the issue.
Counsel for the IFA, David Dunlop, backed his contention that there is no final decision to be challenged.
He further contended that if the legal move was against an Executive policy first set out in 2011 it should be dismissed for being brought out of time.
Following submissions Mr Justice Treacy said he wanted to look at some documents before deciding whether to grant leave to seek a judicial review.