Mensah has been the outstanding performer in Sunderland's last two games and his fitness could prove crucial to the club's fate this season.
Turner hailed the Ghanaian for bringing quality to a back-four which has tightened up considerably since conceding seven goals at Stamford Bridge in January.
In their last six matches Sunderland's defence has been breached only six times, helping to arrest a decline that Turner admits draws an alarming parallel with Hull City's form last season.
The 26-year-old was part of a Tigers side who only escaped the drop by the skin of their teeth after beginning the season with a nine game unbeaten run.
But Turner is convinced that Sunderland are still capable of finishing this season in the top half of the table.
It is a very similar situation.
Hull started very well last season and got stuck in a massive rut they couldn't get out of. I see a similar situation here which we're looking to get out of, he noted.
It is difficult. Players are low on confidence at times and you need that win to get it back. We must take positives from only losing one of the last five.
Players come in and we've not had settled side. We need that for the rest of the season to get us going. It's important to be stable.
As a back four you like to build camaraderie and get it settled. That hasn't been the case but what can you do
Asked if he had played alongside a better defender than Mensah, Turner replied: No, probably not. Unfortunately for him and for us he's not managed to stay fit for a run of games which is disappointing.
He is a top drawer, world class player who we'd like to have fit. He has a lot of great attributes. He is very strong, quick and a calming influence on the ball. He is just a top quality defender.
Turner also noted with approval Anton Ferdinand's recent conversion from central defence to left-back but admits he might struggle to make a similar transition himself.
I wouldn't fancy doing what Anton has done,'' he said. He's a lot quicker than me and on Sunday I thought he did a fantastic job at leftback.
He has been out for a few months and has come back raring to go. That's brought competition for places and that keeps the rest of us on our toes, explained Turner.
The amount of goals we were letting in was alarming but to some degree we've put that right in recent weeks.
Playing at home you can sense the crowd are desperate to have something to cheers about and we want to give them a win.
I feel it can be difficult but we are still 100 per cent behind one another and working hard to get the right result. If we keep doing that I am sure it will come.
You can see how tight it is and it would be nice to go on a run that's what we're aiming for.