'He is a very serious player' - Marcelo Bielsa's tribute to Leeds United youngster he feels he can trust

The central midfielder remained at Elland Road this season when many of his fellow Thorp Arch graduates, like Alfie McCalmont and Robbie Gotts, were sent out on loan to EFL clubs.

Shackleton, still just 21, was seen as part of the first team squad and someone who would be needed as Leeds negotiated their first top flight season in 16 years.

With Mateusz Klich nailing down the box-to-box midfield role and both Luke Ayling and Stuart Dallas ahead of Shackleton in the right-back pecking order, Shackleton was up against it for a starting role in Bielsa's team.

So too was Struijk. The arrival of not one but two international centre-backs in the summer, for a combined sum of over £30m, seemingly pushed him even further down the pecking order, at least for a centre-half role.

Fate, in the form of injuries to both new boys Robin Koch and Diego Llorente, and captain Liam Cooper, have intervened however, allowing Struijk to amass 10 Premier League starts in his natural position. Kalvin Phillips' unavailability has also given the former Ajax academy youngster five appearances in defensive midfield.

All in all, Struijk has racked up 1,191 minutes of Premier League football, having managed only 215 in the Championship. His recent solid displays have helped mitigate for the continued absence of long-term injury victim Koch and Llorente, for whom the season has been disrupted by a series of niggles.

Shackleton, however, has had to be more patient. His first start didn't come until the visit of Leicester City in November and then, after a spell out through injury, a succession of substitute appearances were as good as it got. Two minutes against Crystal Palace followed a four-game stint as an unused substitute, before the injury to Phillips forced Bielsa into a reshuffle and thrust Shackleton into the starting XI.

In the defeat at Arsenal he was a right-back. At Wolves, Bielsa went with something a little different and Shackleton was a midfielder once again, playing alongside Klich.

The pair shared the central defensive midfield duties and although Shackleton went off after 66 minutes, Bielsa was content with what the youngster offered. As he has shown on other occasions this season, whether at right-back or in the middle, he made good decisions on the ball and used his energy to pop up in a variety of areas all over the pitch. His understanding of Bielsa's system almost makes irrelevant the position he's asked to play.

He is a player the Argentine feels he can put his faith in.

"I believe in Shackleton as an important alternative for Leeds United," said the Whites head coach.

"He is in a similar process to that of Pascal [Struijk]. The only thing is Pascal has a continuity that Shackleton hasn't been able to have.

"I consider him a player I can trust, I'm satisfied what he has brought to the team."

Perhaps the greatest tribute Bielsa paid to Shackleton was to laud his professionalism. Despite the limited involvement he's had, certainly in comparison with Struijk's match minutes, the Leeds-born speedster is well aware of what it takes to play for the club in the Premier League, which bodes well for his future at Elland Road.

"He is a very serious player and very applied," said Bielsa.

"He is very conscious of what is needed at this level."

Tonight when Southampton visit Leeds, Bielsa will have Spanish national team defender Llorente at his disposal and therefore could push Struijk forward once more and field an experienced pair in the centre of the defence. If he does, Shackleton is likely to return to the bench. But if he has to call upon Shackleton again, he will do so without reluctance.