Ronan Curtis fired in a double to give Pompey a first away victory of the season at Blackpool.
The summer signing netted his first goals for the club to hand his side a 2-1 win at Bloomfield Road and maintain the Blues’ 100-per-cent win record this term.
However, Matt Clarke’s own goal late on made for a nervy ending, with Mark Cullen having a goal ruled offside at the death.
The Blues almost made the worst start possible when Blackpool's Joe Dodoo crashed a low shot against the post.
Oli Hawkins should have given Jackett's men the lead on six minutes but he headed wide from 10 yards.
However, the deadlock was broken by the Blues through Curtis' first goal since completing his switch from Derry City three minutes later.
Hawkins' header caused confusion among the Tangerines defence and the 22-year-old bundled home a right-footed shot from close range.
Curtis could have had a hat-trick before the break after having a goal-bound shot blocked by Ben Heneghan while he cannoned a 25-yard effort off the far post on 37 minutes.
Blackpool put some pressure on Pompey early in the second half but that man Curtis grabbed his second in the 59th minute.
Hawkins was again the provider, flicking along Craig MacGillivray’s long ball and the Republic of Ireland under-21 international emphatically finished through Howard’s legs to double the Blues’ advantage.
After a fairly solid afternoon for Pompey’s defence, a blip in concentration allowed the hosts to grab a goal back on 81 minutes.
Howard’s long ball ran all the way through to Thompson and while Clarke managed to get a foot in, his challenge lobbed MacGillivray and ended up in his own net.
The hosts thought they’d netted a last-gasp equaliser when Cullen flicked the ball over MacGillivray but he was ruled offside.
Overall, it was a deserved three points for Pompey as they delivered their second win from as many games this term.