Everton established a two-goal first-half lead at Goodison Park – Fraser Hornby rifling home before Con Ouzoundis powered a header past City keeper Ari Muric.
City hit back after the break, however, Phil Foden reducing the deficit before Lukas Nmecha struck twice in quick succession to put the visitors 3-2 ahead.
Everton responded through Shayne Lavery’s close-range finish – after City had Joti Latibeaudiere sent off for a second bookable offence – but England Under-19 international Foden rounded off the scoring to seal victory for City.
The late winner was hugely frustrating for Unsworth, who saw many encouraging signs in his side’s performance – most notably in a first-half display which saw the young Blues negate City while carrying a constant threat in attack.
The boss says it’s vital his players cut out the mistakes which cost them dearly in the second half.
“It was a great game,” he told evertonfc.com. “I thought we were terrific in the first half and we were comfortably ahead.
“In terms of the gameplan and what we’ve asked the boys to do – it was outstanding. We know about Man City, we know they’ve got good players and how they’re going to play, so we’ve been working on that in training – and we stopped them.
"They’re always going to have a level of possession but we wanted to give them that possession in their own half and we knew how to stop that.
“But, unfortunately, in the second half young players have made individual errors and you just hope they learn from that because – when you do play quality teams at any level – they punish you.”
After the hammer blow of seeing their two-goal lead eclipsed by City’s quickfire second-half treble, Unsworth praised his players’ “great desire” to hit back and equalise through Northern Irish striker Lavery.
He also hailed the performance of Scottish frontman Fraser Hornby. The 18-year-old’s strength, link-up play and finishing ability were all on show as he led the line superbly in the first half.
A groin injury forced the Northampton-born striker off just after half-time, which Unsworth admitted was a blow for his side.
“That was one of his best performances,” he said. “And to lose someone of his size and stature, and what he gives us, was disappointing. He’s a player we’ve got high hopes for. He’ll probably have a scan tomorrow (Monday) and we’ll hopefully get him back as soon as possible.”
Unsworth also revealed influential midfielder Antony Evans will miss the rest of the campaign with a knee injury.
“He’s signed a new contract and was captain at the time [of his injury], so to him miss the rest of the season is a massive blow,” he said. “He’s been outstanding for us. But he’ll be back for pre-season.”
For Unsworth now, the focus shifts to a home clash with West Ham United in Southport next Monday (9 April).
The boss says he and his coaching team will use the remaining games to lay the foundations for next season while trying to finish as high up the table as possible – the Blues are currently sixth in Premier League 2 (Division 1).
“We had some decent performances today and we’ll try and win the remaining games,” he said.
“You always look for performance first and with this young group we’re planting seeds for next year – and giving young players opportunities to try and get into our team for next season.”