Hossam Ghaly struck the only goal of the game just before half-time, firing home Jacques Maghoma's low cross to ensure we kicked-off our reserve campaign in winning fashion.
Portsmouth enjoyed the better of the early chances with Daryl Fordyce unable to convert from close range when under pressure from Charlie Lee after only four minutes. The same player was guilty of missing another good chance to break the deadlock six minutes later when his low drive failed to hit the target with Radek Cerny already on the floor after being rounded by Louis Bell.
The home side were having more of the possession but were only able to produce half-chances in the final third and although we were creating less, our goalscoring opportunities were more clear-cut and Portsmouth's young keeper Nick Jordan denied us on a number of occasions.
First he managed to force the ball over the bar with his feet after Jamie O'Hara sent Stuart Lewis through on goal after 17 minutes and he somehow managed to turn over Andy Barcham's shot from six yards after Phil Ifil's cutback just before the break.
Jordan's efforts proved to be in vain, however, when we finally took the lead with four minutes remaining in the first half. Maghoma's low centre from the left flank flew past several bodies but Ghaly was on hand to drill home at the far post.
We almost doubled the lead moments after the restart when O'Hara burst clear before playing the ball inside to Barcham but Jordan was again on hand to deny us, diving at the feet of the pacy forward, and O'Hara failed to convert the loose ball.
We were firmly in control now but somehow failed to add to our tally. Lewis was inches from getting on the end of an excellent cross from O'Hara with Jordan stranded on 49 minutes while the home side's goalkeeper was forced into action again minutes later to deny Jamie Davis.
Anthony Gardner also saw a header from O'Hara's corner headed off the line by Matthew Hartmann.
Cerny was enjoying a far quieter evening between the sticks than his goalkeeping counterpart and wasn't forced to make a save until the 59th minute when he did well to keep hold of a fizzing long-range effort from Fordyce.
Pompey almost snatched an undeserved equaliser 18 minutes from time when Andy Griffin's high ball sent Bell clear of our defence but he fired his shot across Cerny and the goal, ensuring we left the south-coast with all three points.
THE KEY ACTION...
2mins: O'Hara quick free-kick to Maghoma, he cut inside box but shot curled harmlessly over.
4mins: Pompey counter-attack, Harris evaded Daniels' challenge, low pass to Fordyce who flicked just wide from close range.
9mins: Deep O'Hara free-kick headed back across goal by Gardner, Lee couldn't keep headed effort on target.
10mins: CHANCE. Best of early exchanges, Bell managed to dribble around Cerny, laid ball back across the face of goal but Fordyce's low drive failed to hit target with two players on line.
17mins: Lewis denied by feet of Jordan after defence-splitting pass by O'Hara.
18mins: Songo'o found Hughes, edge of box, dragged shot wide.
29mins: CHANCE. Pompey move ended with Hughes sending Bell through on goal but he scuffed his shot at Cerny.
33mins: O'Hara free-kick, centrally, 30 yards out, flew over.
35mins: Maghoma curled shot from left channel of box just wide of right upright.
39mins: SAVE. Ifil cut back to Barcham, six yards out, Jordan managed to block point-blank effort.
41mins: GOAL - SPURS. Maghoma's low centre was missed by everyone in the box and ended up running to Ghaly who blasted home from 10 yards.
Pompey 0, Spurs 1
Added time: McClory-Cuthbertson's corner not cleared properly and Songo'o produced spectacular overhead kick that flew marginally wide.
Half-time: Pompey 0, Spurs 1
47mins: CHANCE. Jordan blocked at feet of Barcham and O'Hara blasted the loose ball wide.
49mins: CLOSE. O'Hara crossed from left, Lewis slid in with goal at his mercy but just failed to make contact.
52mins: Davis breeched Pompey back line but shot palmed away by Jordan.
53mins: OFF LINE. Gardner header from O'Hara corner cleared off the line by Hartmann.
59mins: Hartmann ran through midfield before releasing Fordyce, his effort well held by Cerny.
72mins: CHANCE. Griffin released Bell through on goal but his diagonal low drive just missed the goal frame.
Full-time: Pompey 0, Spurs 1
Pompey: Jordan, Oastler (Ward, 75), Hartmann, Griffin, Wilson, Hughes, Songo'o, Harris, Bell, Fordyce, Ritchie (McClory-Cuthbertson, 23). Subs: Plummer, Roberts.
Spurs: Cerny, Ifil, C Lee, Gardner, Daniels, Lewis, Davis (Livermore, 79), Ghaly, O'Hara, Maghoma (Pekhart, 64), Barcham (Mills, 90). Subs: Stroud, Hughton.
Our reserves kicked-off the defence of their Barclays Reserve League South title with a hard-fought win against Portsmouth at Havant & Waterlooville FC on Wednesday night.