Adam Lallana
Lallana will face Southampton for the first time as a Liverpool player on Sunday. Getty Images

Adam Lallana has expressed regret over the way he swapped Southampton for Liverpool during the summer transfer window.

The 26-year-old moved from Saints for £25 million ($38.6m, €34m) after an impressive campaign on the south coast but an injury-hit season has seen him score just five goals in 27 appearances for his new club.

Lallana was one of six high-profile departures from Southampton during a summer which also saw Calum Chambers, Rickie Lambert, Luke Shaw and Dejan Lovren leave while manager Mauricio Pochettino moved to Tottenham Hotspur.

After missing the visit of Ronald Koeman's side on the opening weekend of the season due to injury, Lallana is expected to feature as Liverpool travel to their top four rivals in his first return to St Mary's since his controversial summer move.

And despite Southampton having enjoyed a decent campaign after Koeman rebuilt the squad in the summer, with the club four points above Liverpool ahead of kick-off, Lallana admits the deal inevitably left a "sour taste".

"I'm not stupid enough to think the way I left didn't leave a sour taste in a few people's mouths," he told BBC Radio Solent. "I regret the way I left. I regret bits and pieces of how it happened and it got nasty. It was sad the way it happened.

"What is true is that when I knew of Liverpool's interest and that they had put a bid in, I did say to the club it would be my wish if they could negotiate a fee for me to move on.

"Not for one second did I say I wouldn't play for the club again. I'm man enough to say it was my choice and my decision for me to move on.

"Deep down I hope Saints fans appreciate the times we had at the club together. Football is a fickle game -- if I do get the jeers and the boos I'm just going to take it as them missing me playing down there because I miss Southampton.

"I miss the fans and I miss the good times we had down there."