Goals from Alfie Bridgman and a Blues triallist in the final of three 30-minute periods did the damage at the Pinatar Arena in Murcia.
The opposition were reduced to 10 men late on following a crude challenge on Harry Jewitt-White, while Sean Raggett also came off with an injury.
But it proved a useful workout for Pompey, who were cheered on by around 200 fans as temperatures soared above 30 degrees celsius.
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With youngster Dan Gifford injured in training, it meant there wasn’t a single striker in the first-team set up.
A 10-man bench included Jayden Reid and a triallist who were also capable of leading the line.
It was Curtis who threatened after just two minutes when he got in behind the Qatar SC defence, but his cross from the byline went out for a corner.
It was the Irishman who again threatened nine minutes later, when he turned over possession and squared but the on-rushing Tunnicliffe couldn’t apply the final touch from close range.
Bass then showed his class to deal with a high backpass from Robertson on the chest, and then knock the ball over the on-rushing Soria before nodding the ball back to the Pompey skipper.
A decent cross from Zak Swanson was just too high for Curtis at the end of the end of the first of the three 30-minute periods being played.
Pompey had a good penalty shout turned down when a flowing move ended with Jacobs being upended in the box by Javi Martinez, but the referee waved the appeals aside.
Play was then stopped in the 45th minute with Sean Raggett receiving treatment. The defender was then withdrawn with Louis Thompson coming on and Marlon Pack dropping into the back four.
Awad mustered a rare shot at the end of the second period, after Freeman had replaced Swanson with the game still goalless.
Eight changes were made going into the third period - including a Pompey triallist who opened the scoring in the 69th minute.
He had good work from Jay Mingi to thank as he threaded a ball through with the striker taking a touch and then burying his finish past the Qatar SC keeper Tosam.
Excellent work from Harry Jewitt-White saw him beat two men and then square to Bridgman whose effort from 20 yards was turned over by Tosam.
But the Crookhorn lad wasn’t to be denied and sealed Pompey’s win, when the triallist rolled his defender and his cross was cleared as far as the third-year scholar who coolly tucked the ball away from 12 yards.