Summer signing James made his second Whites start in Tuesday's third round Carabao Cup clash at Craven Cottage, from which Bielsa's Whites eventually progressed via a 6-5 win on penalties.
The contest ended goalless after 90 minutes, by which point United's side featured two 19-year-old debutantes in Gelhardt and McKinstry who himself had replaced 19-year-old full debutante Crysencio Summerville.
As the game went to spot kicks, Gelhardt and McKinstry were then both required to take penalties as a dramatic shoot out went to sudden death.
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The teens held their nerve to produce impressive strikes from 12 yards out as Leeds went through - capping a memorable day for James who became a dad just a matter of hours before Tuesday's cup tie.
The winger's girlfriend gave birth to a baby boy on Tuesday lunchtime as the couple became parents and James spent a few hours in Manchester following the birth of their child.
The 23-year-old then flew to Craven Cottage by helicopter and played a starring role as Bielsa's Whites put themselves into Wednesday night's fourth round draw.
“I want to thank the manager for letting me stay up in Manchester to see my baby's birth," said James to LUTV.
"It was absolutely amazing and thankfully the baby was born just in time for me to get down for the game.
"It’s double happiness!
"As soon as the baby was born I had about an hour with the missus.
"We had our own time which is obviously nice and I ended up flying from Manchester on helicopter.
"It was nice, I got here and I played a full game and thank you again to the manager for letting me do that."
Reflecting on Tuesday's game in which Leeds squandered lots of chances in the first half - and then saluting the club's youngsters - James said: “I think maybe we were disappointed because we created a lot of chances to go and win the game in normal time.
"But thankfully the boys stepped up and put the pens in the back of the net.
"All credit to the young boys that came on as well, they did so well and they stuck their penalties away.
"Full credit to them.
"It's not easy to stand up, come on for their debut and take a penalty.
"The number of penalty they were at, they maybe thought they wouldn't have taken one but you have got to be ready and they certainly were."
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Thank you Laura Collins