A rotated Pompey Academy side battled to a 2-2 draw against Cheltenham Town in the Youth Alliance southwest division.
Alfie Stanley and Oscar Johnston were on target for the young Blues.
Pompey were without Matt Casey and Bradley Lethbridge, after they were called up to the first-team squad to face Northampton in the Checkatrade Trophy.
As a result, a number of under-16s were called up for the clash.
The hosts made a poor start and fell behind on seven minutes when George Lloyd headed home from six yards.
The Blues responded well and in the 15th minute Matt Mayes should have done better when he was put through on goal by Harry Kavanagh, but blazed over the bar.
Six minutes from the interval, Mayes was brought down on the edge of the Robins box.
The Pompey captain took the free-kick and forced a good stop from Cheltenham goalkeeper Lewis Clayton.
The Blues rode their luck in the 74th minute when the visitors rattled the crossbar.
But five minutes later, the hosts equalised when Joe Hancott intelligently picked out Stanley in space inside the box and the under-16 talent guided his effort home.
The Blues thought they had grabbed the winner one minute from time.
After a scramble inside the Cheltenham box, the ball fell to first-year scholar Johnston.
The winger kept his composure and crashed a left-footed effort beyond Clayton.
However, Pompey were unable to see out the game.
Deep into injury time, a Robins free-kick picked out Will Dawes and he played the ball across goal for Archie Brennan to tap home.
Nevertheless, it was a solid performance from a team mainly made up of first-year scholars and under-16s.
Pompey next face Leicester in the FA Youth Cup third round at Fratton Park on Tuesday (7.45pm).