EFL Reporter @simgholam
Leeds vs Derby: Harry Wilson, Jack Clarke and Jayden Bogle among the youngsters who will be on show at Elland Road
Watch Leeds vs Derby live on Sky Sports Football from 7pm on Friday night.
Last Updated: 11/01/19 7:51pm
Leeds and Derby have both made excellent use of some of the best young talent in the Sky Bet Championship this season.
Ahead of their meeting on Friday night, which is live on Sky Sports Football, we take a look at seven players aged 21 or under who could star in the clash at Elland Road...
Aapo Halme - Leeds
As Leeds' injury problems have built up in the last couple of months Bielsa has been forced to turn to his 20-year-old Finnish defender to plug a gap at the back in the past few weeks.
He joined from Finnish club HJK Helsinki in January last year but did not make his first appearance until November. He has featured in four Championship games so far but Leeds have won all four, and conceded a single goal in the process. He also scored his first goal for the club in their 2-1 FA Cup defeat to QPR last weekend.
A suspension for Kalvin Phillips means Halme could be used in central defence again against Derby. He is a big presence at 6ft 5ins and also is useful with his feet, fitting Bielsa's requirements for a central defender well.
Jack Clarke - Leeds
The baby-faced winger made his debut in October and he has since gone on to score twice in 12 appearances for Leeds.
Aged just 18, he has been used as an impact substitute in all of his Championship appearances so far, but did make his first start in the FA Cup tie at QPR.
His major contribution came in the Championship classic at Villa Park last month, as his second-half introduction and first senior goal triggered a comeback from two goals down to win 3-2.
Jamie Shackleton - Leeds
Another Leeds academy product who has made quite a big impression this season is 19-year-old full-back Shackleton.
He was handed a first start by Bielsa way back in their Carabao Cup victory over Bolton in August, and has made 15 appearances in total this season, playing regularly in December, in particular, to fill in for the injured Luke Ayling.
Bielsa has been impressed. "Jamie has a maturity which does not correspond to his age. He plays like a veteran but he's only 19," he said last month.
Jayden Bogle - Derby
Derby boss Frank Lampard has not been forced into playing youngsters by injuries in the same way as Bielsa, instead opting to promote youth in a bid to lower the average age of what was an old squad under Gary Rowett.
Bogle, 18, made his first appearance in the Carabao Cup in August and has been a virtual ever-present at right-back since. Aside from a freak own goal that cost Derby victory against Middlesbrough in October, he has been a superb addition to Lampard's side.
Even at his tender age, Bogle already appears to possess all the credentials to become the perfect modern full-back. He is resolute in defence and also a pacy asset going forward.
Fikayo Tomori - Derby
It was not an easy introduction for Chelsea loanee Tomori in August, with his first appearance coming in the 4-1 hammering at home to Leeds in Derby's second game of the season.
But since then he has established himself as a vital cog at the back for the Rams, breaking up the partnership of Richard Keogh and Curtis Davies that was so impressive under Rowett.
The 21-year-old has endured one or two shaky moments at Pride Park, but he fits Lampard's style perfectly in how he wants to play out from the back and will likely attract Premier League interest in the summer.
Mason Mount - Derby
Derby's second Chelsea youngster, Mount made a fantastic start to life in the Championship, scoring in their opening game of the season as they came from behind to beat Reading, and a run of five goals in his opening 11 appearances led to an England call-up in October.
In truth his form has dipped a little since as he becomes accustomed to the pace and intensity of the English second tier, having spent the previous season on loan at Vitesse in the Eredivisie.
Lampard still has full faith in his loanee, who turned 20 on Thursday, and he remains a mainstay in his midfield. It was vindicated when Mount scored his first goal since September in the incredible 4-3 win at Derby last month.
Harry Wilson - Derby
Lampard also headed over to Liverpool to acquire the talents of 21-year-old Wilson in the summer, who has caught the eye with some spectacular long-range strikes this season.
The Wales international is Derby's top scorer in the Championship with nine and their joint-top scorer in all competitions with 10. His free-kick at Manchester United in the Carabao Cup in September, especially, will live long in the memory.
There had been talk last month Wilson would return to Liverpool to bolster their squad for their Premier League title challenge, but he seems set to stay at Derby and help with their promotion push for the rest of the season.