Shackleton featured for Leeds in their 2-1 win against QPR at Elland Road in the Championship on Saturday afternoon.
The 19-year-old right-back started the game and played for the entire 90 minutes, and Leeds head coach Bielsa was impressed.
Leeds Live quotes Bielsa as saying about Shackleton: “When we dominated the game he was influential.
“He had no problems in defence, he is a player with personality. He is not impressed by the importance of being in the first team.”
Shackleton is only 19 years of age and has made only a handful of appearances for the Leeds first team, but the youngster is showing a lot of confidence and maturity.
The talented and promising teenager worked hard, contributed in attack and defended well, as the Whites maintained their challenge for automatic promotion to the Premier League.
According to WhoScored, Shackleton took one shot, had a pass accuracy of 94.4%, won two headers, made one clearance, and made one key pass.
The win against QPR means that Leeds are now second in the Championship table with 42 points from 21 matches, just a point behind leaders Norwich City.