Sadio Mane called time on his Liverpool career after completing a £35m move to Bayern Munich on a three-year contract last summer.
The Senegal international was a joy to watch on the Reds' left-wing, forming a dynamic partnership with Robertson, making 203 appearances together.
He netted 120 goals in 269 games, finishing last season with 23 goals across competitions.
Jurgen Klopp's side have underwhelmed this season and are currently fighting to finish in the top-four as they lie sixth with 42 points, seven points behind fourth-placed Tottenham with a game in hand.
The Merseysiders were eliminated from UEFA Champions League following a 6-2 aggregate loss to Real Madrid, while they were knocked out from both the FA Cup and Carabao Cup.
However, Robertson believes Liverpool's problems are not down to Mane's exit.
The Scotland skipper has told BBC Radio 5 Live: “To be honest, no. Don't get me wrong, I had a fantastic relationship with Sadio in terms of me and him down the left-hand side for five years."
"He was a joy to play with, every game. I loved playing with him, we linked really well. He helped me going back, the way I helped him going forward. And yeah we linked up really well. When he left, there was probably no-one more gutted than me because of the relationship we had.
“But we've got fantastic players that can play in their positions. We brought in Darwin, who has been really good to start.
"We've got Luis Diaz who has obviously been injured and re-injured and things like that, which is difficult. Jots [Diogo Jota] can play there, who's got injured. We have been a little bit unlucky with injuries, I think once we get them back fully fit then yeah.
"Look, Sadio was a wonderful player, a Liverpool legend but he wanted to go and he went to Bayern Munich and we wish him all the best.”
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