The Manchester United and England striker will be questioned over his involvement with controversial football agent Paul Stretford, who represented the player for six years.
The young football prodigy, then aged 17, was signed up by Stretford in 2002 as he burst onto the football world with his home-town club Everton.
Mr Stretford, a founder and director of the sports management firm Proactive, brokered multimillion-pound deals with firms including Nike and Coca-Cola for Rooney.
Mr Stretford also acted for Rooney's wife Coleen, whose celebrity career took off as the player established himself as an England regular following his £20 million transfer to Manchester United in 2004.
The deals agreed to pay Proactive 20% commission but, after Mr Stretford left the firm in acrimony in October 2008, no further commission payments have been paid.
Proactive's lawyers claim that, under the terms of the contract Mr Stretford signed with the Rooneys while he was working for the firm, they are still due the commission payments - now amounting to a minimum of £4.3 million.
Rooney, 24, is expected to give his evidence when the hearing, now in its second week, resumes at Manchester Mercantile Court.