The Gulls edged home in a breathless five-goal thriller at Plainmoor, with Knill saying: "Lee was absolutely outstanding.
"He drove the team on and led by example. He's everything you want in a team player - energy, aggression and he's got a fair bit of quality too."
Torquay deserved a 1-0 half-time lead, given to them by on-loan Southend striker Elliot Benyon's 25th-minute header. But, in a second half of non-stop action, a masterful substitution by Barnet player-manager Edgar Davids paid big dividends.
The Dutchman brought on Jake Hyde in the 58th minute, and the striker equalised with his first touch seconds later, nodding home from point-blank range after Michael Poke parried Harry Crawford's first effort.
Torquay picked themselves up to regain the lead through Billy Bodin's left-wing shot only a minute later, and then Saah grabbed his first goal of the season to make it 3-1, with a clever, looping header from Mansell's corner in the 71st minute.
But even then Barnet would not lie down, and Hyde set up a nail-biting finish when he produced a stunning first-time volley from Luke Gambin's cross in the 77th minute.
"I'm delighted not just with the result, but the performance," said Knill. "We asked for big displays from everyone tonight. We needed everybody to play well, and I'm thankful that they did."
Davids said: "It's always very frustrating to concede goals from set-pieces, especially as we did it just after we had got back to 1-1.
"We have to show real character to get out of the relegation zone. Teams have come from a long way behind to escape, and we must do that now. The Barnet fans will be vital when we play Wycombe on Saturday."
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