A-League champions Adelaide United sign Socceroo James Holland

Adelaide United have secured fringe Socceroo midfielder James Holland for the upcoming A-League season.

The Reds have beaten several A-League rivals to sign Holland, who has 15 national caps and spent the past seven years playing in the Netherlands, Austria and Germany.

Adelaide, the reigning A-League champions, are also closing in on signing Spanish striker Sergi Guardiola for the domestic season which starts next month.

Holland, a member of Australia's 2014 World Cup squad who has since drifted from the thoughts of Socceroos boss Ange Postecoglou, will be unveiled as an Adelaide signing on Wednesday.

The 27-year-old is understood to have agreed to a two-year contract with the Reds, who also soon hope to confirm the recruitment of Guardiola.

The Spaniard, no relation to world-renowned manager Pep Guardiola, has agreed in principle to a stint at Adelaide after his La Liga side Granada's released the 25-year-old on loan.

The signings bolster an Adelaide outfit depleted by the off-season departures of the likes of title-winners Bruce Djite, Stefan Mauk, Craig Goodwin, Bruce Kamau and Pablo Sanchez.