Northern Ireland opened their Pinatar Cup campaign with a 1-0 loss to Iceland in Murcia.
Iceland midfielder Dagny Brynjarsdottir scored the game's only goal on 24 minutes when her cross fortuitously looped into the net.
The defeat leaves NI manager Kenny Shiels without a win after five games in charge.
Northern Ireland will face Ukraine on Saturday before concluding their campaign against Scotland on Tuesday.
Northern Ireland looked to impose themselves on the game from the outset with Durham midfielder Sarah McFadden shooting over the bar.
NI enjoyed several spells of possession in punishingly hot conditions in Murcia, with Shiels' attacking trident of Megan Bell, Lauren Wade and Simone Magill causing the Icelandic defence plenty of problems.
However, Iceland soon ramped up the pressure on the Green and White Army with Jackie Burns producing a fine save to deny striker Elin Jensen.
There was nothing Burns could do to stop Brynjarsdottir, however, who struck the opening goal after 24 minutes when her cross from the right wing looped over the NI keeper
Undeterred, Northern Ireland continued to trouble their opponents and came close to an equaliser within 10 minutes of going behind when Wade saw her effort turned over for a corner by Cecilia Runarsdottir.
Rachel Furness passed up a decent opening to net the equaliser when the Liverpool midfielder was played through by McFadden, only to fire her right-footed shot straight at Runarsdottir.
Northern Ireland will look to bounce back in their second tournament game, which sees them take on Ukraine on Saturday.