Ben Davies is out to get Derby’s season back on track.
But he admits toppling his former manager at Fratton Park is going to be a tough ask.
Davies played under Steve Cotterill at Notts County last season, storming to the League Two title in the process.
Cotterill took over from Hans Backe in February 2010 and led them to 14 wins in 18 matches.
Midfielder Davies emerged as a key performer and made the switch to Derby last month.
Nigel Clough’s men have now lost nine of their past 11 matches in all competitions during a shock plummet down the league.
As for Pompey, they have failed to win in their past nine matches and continue to ship goals.
It’s a clash between the Championship’s two out-of-form sides.
And Davies is fearful Cotterill can mastermind another bad day for Derby.
He said: ‘It will be tough. I know Steve Cotterill well and I still speak to him quite a bit.
‘I spoke to him just before I moved to Derby and he wished me all the best and everything.
‘He is a good manager and will have his team up for it. He knows exactly what he is doing.
‘When you play against one of his teams, you know it is going to be competitive.
‘And he’s got some good players there – international players.
‘It’s a tight ground and there is always a good atmosphere.
‘Steve was telling me how tough it has been at Portsmouth but he is doing a good job in difficult circumstances.
‘He’s a top-drawer manager and I wish him all the best – after tomorrow, of course.
‘Hopefully, I can get one over on him.
‘If we can play like we did against Ipswich but with a bit more luck, we’re more than capable of winning the game.’
Derby visit Fratton Park on the back of four successive defeats.
But Pompey haven’t won at home since October 30 – when they defeated Nottingham Forest.