Troubled former Olympic swimming champion Grant Hackett has settled a lawsuit against two legal firms over a pre-nuptial agreement with his ex-wife, singer and actress Candice Alley.

The case had been set down for a five-day trial starting on April 18 - the day after Hackett was thrown off a Virgin flight from Adelaide for allegedly giving another passenger a nipple cripple.

Hackett, 35, admitted to having been intoxicated on the 6am flight last Sunday after missing out on selection for the Rio Olympics but denied being under the influence of the prescription drug Stilnox.

He has not been charged over the in-flight incident, but police are still investigating.