Derby centre-back Shaun Barker is set to undergo knee surgery this week.
The Rams confirmed that the defender was to have an operation to 'wash out' his knee and is due to go under the knife on Thursday afternoon.
The 27-year-old, who won the club's player of the season award after playing a crucial part in his team's battle against relegation, is expected to be ready for the new Championship season in August.
Barker is not the only Rams player going into surgery, with winger David Martin also set to have an ankle operation later in the month.
"Both are routine operations and would normally have taken them out of action for four to six weeks," manager Nigel Clough told the club's official website.
"Both will have a week or two prior to pre-season to do some work and get themselves in a good shape ahead of the hard work that pre-season brings."
Derby have also seen strikers Steve David and Rob Hulse undergo surgery on respective ankle and hernia problems, whilst midfielder Stephen Pearson also had a knee operation which is likely to see him miss the opening games of the new season.