Derby County are skating on severely thin ice as they continue to stare relegation to League One right in the face.

The Rams have now lost four on the bounce and fell to a disappointing 3-0 defeat to Preston North End at Deepdale last night.

To put it simply, Derby's fate is no longer in their hands. They will have to rely on Rotherham United, who have three games in hand on the Rams and sit four points adrift of safety.

Far too many players have underperformed this season in what has been a turbulent campaign both on and off the pitch.

Perhaps the most frustrating thing about Derby's squad is that, on paper, there are some excellent individuals capable of playing much better.

But the fact of the matter is, football isn't played on paper, it's played on grass, and Derby look like a team bereft of confidence at the moment.

In regards to individual quality, we've had a look at 10 Derby players who have had the biggest market value increase since making their debuts for the club - as per Transfermarkt...

Martyn Waghorn moved to Derby from Ipswich Town in the summer of 2018, on the back of scoring 16 goals in 44 games for the Tractor Boys under Mick McCarthy in 2017/18.

In his first season at Pride Park, Waghorn scored 13 goals under Frank Lampard in all competitions, before the manager left for Chelsea at the end of the season.

The goals have dried up for him since, though. Last season, he scored 12 goals in the Championship, but has only found the net on three occasions this term.

When he joined Derby, his market value on Transfermarkt was £1.35million, compared to today's value of £1.8million.

In fairness to Byrne, he has been one of Derby's better players this season.

The right-back joined Derby from Wigan Athletic in the summer after the Latics entered administration and were forced to cash in on their best players.

Byrne registered eight assists for Wigan last season, and this season, he's made 38 appearances for Derby, registering three assists for the Rams.

When he joined, his market value on TM was £720,000, and that has risen by £630,000 to £1.35million.

Many players have flattered to deceive this season, but Byrne has provided plenty of attacking presence down the right flank.

Shinnie penned a pre-contract move from Aberdeen to Derby in the summer of 2019, penning a three-year deal at Pride Park.

It took Shinnie a while to make an impact under Phillip Cocu and made his full league debut at the start of October in a 2-0 home win over Luton Town.

The midfielder has since been a regular under both Cocu and Wayne Rooney, making 67 appearances for the Rams across all competitions.

This season, he's made 38 league appearances, scoring three goals.

When he joined, his market value was £765,000, but that has now risen by £855,000.

Lawrence joined Derby from Leicester City for a reported fee of around £5million in the summer of 2017.

Lawrence had previously impressed on loan with Ipswich Town, scoring nine goals and registering 11 assists in the 2016/17 campaign.

But he moved to Derby in 2017/18, scoring six goals and chipping in with eight assists to help Derby reach the play-offs under Gary Rowett.

Since making his debut for Derby, Lawrence has scored 25 goals and made 19 assists in 143 appearances for the Rams.

At the time of when he signed, his market value was perceived to be £2.25million, but that has now risen by £1.35million.

Buchanan is one of many academy graduates currently earning plenty of game time under Wayne Rooney in the first-team.

The left-back made his debut for Derby in the Carabao Cup against Scunthorpe United last season, scoring the game's only goal in a 1-0 win and picking up the man of the match award.

Since making his debut, the young full-back has made 42 appearances for Derby. He's made 33 appearances in the Championship this season, registering two assists.

His market value was obviously £0 when he first made his debut, but his value is now £1.8million since breaking into the first-team.

Clarke was seen as one of the best defenders in League One before he left Portsmouth for Brighton and Hove Albion in 2019.

But the defender is still yet to make a first-team appearance for the Seagulls, having spent the last two seasons on loan with Derby.

Clarke has greatly impressed during his time at Pride Park, making 78 appearances across his two seasons with the club and scoring one goal.

Since joining Brighton and making his debut for Derby compared to now, his market value has risen by £2.52million.

He's been a key player in defence and Brighton will be keen to see him in action next term.

Sibley was earning rave reviews for Derby's Under-23s' before stepping up to the first-team under Phillip Cocu last term.

He hit the ground running in the first-team, scoring a tremendous solo effort on his home debut against Blackburn Rovers before lockdown.

After lockdown, he scored a hat-trick in a big away win at Millwall, before ending the season with five goals to his name.

He's ultimately failed to replicate that form this season, but is still a raw player with plenty of potential.

His market value has risen to £2.7million since stepping up to the first-team.

Bielik has endured plenty of lows since joining Derby from Arsenal for around £10million on a five-year deal last season.

Whenever he has played for Derby, the Poland international has proved his worth, showing that he is a class act with some tremendous performances in the middle of the park.

But two serious knee injuries have sidelined him for the worst part of 14 months, limiting him to only 34 appearances across two seasons.

He has been desperately unlucky with injuries, and Derby have missed him during his absence.

When he made his debut for Derby, his market value was £1.8million. That has now risen to £4.5million, which is a difference of £2.7million.

It's hard to remember that Bird actually made his debut for Derby in an EFL Cup clash with Barnsley back in 2017.

The midfielder has since racked up 68 appearances for the Rams in the first-team, having played at every youth level for the club.

This season, he has been a key player in the middle of the park having racked up 31 appearances in the Championship.

Since making his debut for the Rams, his market value has risen by £3.15million and is undoubtedly set for a good future.

Knight has been one of Derby's few bright sparks this season.

The midfielder was given his debut for Derby in Phillip Cocu's first league game in charge last term - a 2-1 win away at Huddersfield Town.

This season, he has gone from strength to strength, making his debut for the Republic of Ireland national team last October against Finland.

This season, he was given the captaincy by Wayne Rooney in his first game as a coach, and is undoubtedly set for a bright future.

Since making his debut for the Rams, his market value has risen to £4.5million.