Canter entered the weekend at Chervò Golf Club with a two shot lead and three closing birdies moved him to 19 under after a 69 as he looks for a first European Tour win.
But McGowan made gains on three of his last four holes in a 67 that saw him join his fellow Englishman at the summit.
South African Dean Burmester was the closest challenger after a 68, a shot clear of Belgian Nicolas Colsaerts and German Sebastian Heisele, and two ahead of Spaniard Adri Arnaus and Finn Tapio Pulkkanen.
Canter made his European Tour debut as an amateur at The Open Championship in 2010, the same year that McGowan came within a whisker of making the European Ryder Cup team after a 2009 season that saw him win the Madrid Masters and finish 12th on the Race to Dubai.
Since then both men have been regulars at the Qualifying School, with both graduating in 2015 and 2017, while Canter also earned his card via that route in 2016 and 2019.
McGowan has had just one European Tour top ten in the last four seasons but won last year's D+D REAL Czech Challenge on the European Challenge Tour for a first professional victory since 2015.
"A win would probably change the outlook for the rest of the year, next year and hopefully for the next few years after that," he said. "I’m not getting any younger so it would be quite handy to win one nice and early.
"Definitely my putting has been my best strength this week. It’s helped me in the first two rounds when I hit maybe six fairways. Even today I hit more fairways but not enough, but I rolled a few nice ones in - a couple of 30 footers - and that kept the score going."
Canter claimed his first top ten at the 78th time of asking in August but now has three in his last eight starts and is going in search of a wire to wire victory after carding the lowest round of the season with a 60 on Thursday.
"I definitely feel confident I can go out and stick to what I’m doing," he said. "I don’t know if that will be good enough.
"I have a feeling tomorrow a few people a couple of shots back will pull the anchor up and go for it and somebody’s going to go low tomorrow, so Ross and I and those around us will have to keep going forward to be up there. I like how I feel out there so we’ll see how I feel then."
McGowan holed a 25 foot right to lefter on the second to get within one and a two shot swing on the par five fourth had him in the solo lead.
Canter had a rotten stroke of luck as an impressive looking tee shot hit the power lines, meaning he had to play again, and the second effort went in the water without a deflection leading to a bogey.
McGowan, meanwhile, played the hole in textbook fashion to take the lead but then slipped back into a share after hitting a poor chip on the fifth.
Another 25 footer on the sixth brought McGowan an eagle but he only led by one as playing partner Canter made a birdie at the same hole.
Burmester's second at the par five was even better than McGowan's, and the 31-year-old holed from ten feet for an eagle of his own to go with a birdie picked up on the par five fourth.
McGowan hit a poor tee shot on the seventh and failed to get up and down from the sand on the ninth to put Canter in the solo lead and all three of the final group made the most of the par five 11th.
Both Burmester and Canter then three putted the next and we once again had a tie at the top.
McGowan holed a brilliant 30 foot right to lefter on the 15th and made it back to back gains from 15 feet on the next, where Canter also picked up a shot from close range.
A tee shot to ten feet on the par three 17th put Canter back into a share of the lead and the leading duo both took advantage of the last, with Burmester completing a birdie-birdie finish after a bogey on the 16th.
Colsaerts birdied the two par fives on the front nine and added another on the seventh before birdieing the 12th, holing from 25 feet on the 13th and taking advantage of the last in a bogey free 66.
Heisele sandwiched a bogey on the fifth with birdies on the par fives and added gains on the 11th, 13th and 15th before a 22 foot eagle putt on the last catapulted him up the leaderboard.
Arnaus and Pulkkanen both made seven birdies and two bogeys in their rounds of 67 to sit a shot ahead of defending champion Bernd Wiesberger, two time Major winner Martin Kaymer, Northern Ireland's Jonathan Caldwell, South African Louis de Jager and Dutchman Darius van Driel.