Pompey have signed centre-back Regan Poole following his departure from Lincoln at the end of last season.
The 25-year-old Welshman – who will wear the number five shirt – has put pen to paper on a two-year contract at Fratton Park.
Blues boss John Mousinho said: “Regan brings a lot of league experience, having played at a consistently high level for Lincoln over the past few years.
“That included taking them all the way to the play-off final and he has also worn the captain’s armband.
“He’s a versatile defender and is very good on the ball, while being aggressive off it, and has excellent qualities.
“In terms of the all-round package of playing and leadership, we’re getting someone who’s very exciting.
"Regan brings a lot of league experience, having played at a consistently high level for Lincoln over the past few years."
“We probably won’t see him play in the friendlies this week, but he’ll come in and train with us straight away.
“We were thrilled to take nine new players away with us to Spain and it’s important that we get these signings in as soon as possible to get them used to the way we want to do things.”
Poole progressed through the ranks at Newport County and became their youngest ever player when he took to the pitch against Shrewsbury, aged just 16 years and 54 days.
He caught the eye of Manchester United and made his only senior appearance for the club in a Europa League win over FC Midtjylland.
After spending time out on loan, the former Wales under-21 international signed for MK Dons and then joined Lincoln at the start of 2021.
Poole made a total of 131 appearances for the Imps and started at Wembley when they were narrowly beaten by Blackpool in the League One play-off final at the end of his first campaign with the club.
He was named their 2021/22 Player of the Season by both supporters and fellow team-mates.