Manchester City boss Sven-Goran Eriksson has given young goalkeeper Richard Martin a one-month contract.
Eriksson is without keeper Isaksson for six weeks
The former Brighton player, 19, has been training with City recently and featured in a reserve team game at Accrington last weekend.
With first-choice keeper Andreas Isaksson out for at least six weeks with a fractured finger, Eriksson wants additional goalkeeping cover.
Joe Hart and Kasper Schmeichel are City's other goalkeepers.
City open their Premier League campaign at West Ham on Saturday.