Tonda Eckert made three changes to the team that started on Wednesday in the home win against Sheffield United. Southampton hadn't won at Fratton Park in the league since 1976 before today's match.
Sticking with a 4-2-3-1 formation, the Saints looked more balanced from front to back. James Bree started the match at right back, with Matsuki a surprising starter ahead of Tom Fellows.
Jack Stephens kept his place at centre-back alongside Taylor Harwood-Bellis, displacing both Nathan Wood and Joshua Quarshie.
Wantaway striker, Adam Armstrong, returned at the expense of Ross Stewart, who played sixty minutes on Wednesday night.
Saints unlucky not to be ahead early
Southampton were unlucky not to be ahead in the eleventh minute when Finn Azaz slid Adam Armstrong in. Armstrong kept his shot down from 12 yards out but was unable to steer the ball wide of the keeper, who saved well with his feet.
Only a great save by Nicolas Schmid in the nineteenth minute denied Armstrong again. The Saints striker struck his volley well from close range, but the Pompey keeper did well to make a reaction save.
Millenic Alli shot tamely wide for Portsmouth in the 22nd minute when he should really have hit the target.
Welington was in the wars in the first half; a nosebleed forced him off for a few minutes. He made an excellent block on a Chaplin volley midway through the first period, deflecting the ball over the bar for a corner.
Jack Stephens made an excellent challenge to deny Colby Bishop a certain goal, a reminder of the threat that Portsmouth possess.
Robust in the challenge but devoid of good possession
Southampton were robust in the challenge throughout the first half, but unable to get control of possession.
Portsmouth had nine shots compared to Southampton's three in the first half. However, Saints created the better chances and hit the target twice.
Pompey's efforts, in contrast, were a weak header that looped up into Peretz's hands and a blocked volley.
Half-Time: Portsmouth 0-0 Southampton