The Iron's academy side were held by Lincoln City in a six-goal thriller on Saturday morning at Ashby Avenue.
Leslie Sackey netted a brace, before Jack Dyche thought he'd won the match for Scunthorpe with only a late strike from the Imps forcing a sharing of the spoils.
The game was marred late on by an injury to defender Riley Baker who will now miss six-to-eight weeks with a broken ankle.
INJURED: Defender Riley Baker will be out-of-action for six-to-eight weeks with a broken ankle.
It was United who broke the deadlock inside ninety seconds with a good team goal. The ball found itself down the left-hand-side before being played inside to James Dean-Atkinson. He played a good ball through to Jack Dyche, who controlled and found Sackey, who was able to play the ball past the goalkeeper.
The equaliser came on 54 minutes via Millington before Harris converted from the penalty spot ten minutes later after a foul by an Iron defender.
Ten minutes later, in the 74th minute, the scores were level once more as Sackey got his second, rounding off another neat move after again being played through.
Four minutes later, Scunthorpe re-took the lead via Dyche and it looked as though the Iron would hold on for three points until the tenth minute of stoppage time.
Baker was the recipient of a challenge soon after which saw him break a bone in his ankle, with the time added on giving Clarke enough time to level the scores in the 100th minute.
Academy manager Tony Daws said: "It was an entertaining game and the lads did really well.
"We started the game really well and we felt we'd done enough to win the game. We competed well and created more chances, but credit to Lincoln they made it tough for us.
"Riley sadly broke a bone in his ankle. There was no malice in the challenge whatsoever and it looks like Riley will be out for six-to-eight weeks. He's a fantastic lad with a great attitude with so much enthusiasm and commitment.
"We wish him a speedy recovery and full rehabilitation from it."
IRON TEAM: Parker, Baker (Tolchard), Cleminshaw, Butroid, Sithole, Dean-Atkinson, Shilling, Hornshaw, Burdett, Dyche, Sackey (Ablett)
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