Liverpool manager Jurgen Klopp has said midfielder Adam Lallana showed courage to move out of his "comfort zone" when he left Southampton.
Lallana, 28, made a £25 million move to Anfield in 2014 after having been with Southampton since the age of 12 and helped them win back-to-back promotions from League One.
Both he and ex-Saints defender Dejan Lovren, also now at Anfield, return to St Mary's as Liverpool face Southampton in the EFL Cup semifinal first leg on Wednesday.
Klopp said Lallana had been right to make the switch to Merseyside and told a news conference: "I'm not here long enough to know why Southampton fans react as they do but he is a boy from the region -- that's how it is.
"His friends and family all come from there, he comes from there, and with his quality I can imagine everybody at Southampton thought he could be the player for the next 10-15 years to build a team around.
"But actually I'm really happy he decided differently and wanted another challenge and experience.
"He has made outstanding, big steps from an already high level -- that is not always expected, and you cannot be sure he would have done the same at Southampton."
The manager said that, in Lallana's earlier days at Liverpool, "I heard that nobody was really happy about his performances -- and especially himself probably, from what I know of him."
He added: "So it's clear he needed this kind of step back to make the next step in the right direction. He left the comfort zone, if you want."
Lallana has thrived in a central midfield role under Klopp this season, with former Liverpool defender Jamie Carragher describing him as "England's best player."
And Klopp said he felt Southampton fans would come to appreciate their former player's improvement.
"I would hope that at some point they can be proud again that a boy from their region is rated so highly in English football," he added.
"Probably one day when they sit at home and think back they will think it's nice that he made this development."
Meanwhile, Alberto Moreno said he wanted Liverpool to secure a solid advantage in the semifinal with a positive result at St Mary's.
The left-back told the club's official website: "I think that's the most important thing, to go down there and make sure we come back with something positive because we've been lucky enough in the draw that we play the second leg in front of our own fans at Anfield.
"I'm not saying it hinges on it, but it would be very good to make things easier in the second leg."