Peter Lawrie and Paul McGinley lead the Irish challenge but it was the late comebacks from rookie pro Gavin Moynihan and veteran Pádraig Harrington that caught the eye at the 72° OPEN D'ITALIA presented by DAMIANI.
Making his professional debut on his 21st birthday, Moyniohan birdied his very first hole and then struggled before a birdie-par-birdie finish for a 73 left him three shots outside the projected cut mark alongside Simon Thornton and Kevin Phelan on one over par at Golf Club Milano.
It’s a finish that gives Moynihan a fighting chance of making the cut on his debut. And there was also a positive end to the day for Harrington, who was one over with five holes to go before he birdied the par-five 14th and eagled the par-five 16th to post a two under 70.
Having struggled to hole putts in The Netherlands last week, Harrington again holed little on a day when he had to scramble eight times and pulled it out on six occasions.
His 70 left him tied with European Ryder Cup captain Darren Clarke, who had an eagle and four birdies in his 70.
Nicolas Colsaerts produced a sensational run of eight consecutive birdies as part of a flawless nine under par 63 to charge to the top of the first round leaderboard.
The big-hitting Belgian fired eight birdies in a row from the 14th to the third and added another on the eighth to finish the day two shots clear of Francesco Molinari, Shiv Kapur and Kristoffer Broberg.
Lawrie needs one big week to regain his card as he sits 121st in the Race to Dubai some €25,000 outside the Top 110 who have full playing privileges for 2016.
And he made a great start with six birdies in a four under 68 leaving him tied for 22nd with McGinley, who who dropped just one shot in a very tidy round.
Colsaerts has not had a win since the Volvo World Match Play Championship in 2012 and sits 100th in the Race to Dubai after securing just two top ten finishes this year.
But the Ryder Cup hero from Medinah insists his game is not that far away and was delighted to see things come to fruition at the Golf Club Milano.
The 32 year old had a good look to make it nine birdies in a row on the fourth but his putt from 15 feet just missed.
With preferred lies in play, Colsaerts' name will not go in the history books but he was just the 11th player to make eight birdies in a row on the European Tour – the first being the great Seve Ballesteros at the 1985 Italian Open.
Home favourite Molinari also started on the tenth and picked up shots on the 12th, 14th, 16th and 17th to sit four under after nine holes. A further birdie followed on the fourth but he gave the stroke straight back before finishing with three gains to sit seven under.
Kapur made the turn two under after a bogey and three birdies on the front nine but four consecutive gains from the 12th and another on the last saw him sit alongside Molinari and Broberg, who finished with five birdies.
The Swede was two under through 13 holes thanks to four birdies and two bogeys but his surging finish took him to seven under and into a share of second place, two shots behind Colsaerts.
“It all felt pretty easy to be fair,” Colsaerts said. “We all know what it is like to catch fire and get on a run like that but I didn’t realise how many birdies in a row I had made until the sixth one, then I started to count them.
"I actually could have made nine in a row but the putt just took a little bobble at the end which took it offline.
“It felt like I could have birdied every hole today. I think I only had one really long putt but the rest of them were all pretty makeable and it was just one of those days.
“I have been playing quite well for a while and waiting for a round like this when it all comes together. Today it was great and it is nice to see the work you are doing paying off for a change.”
“The course is not long and the back nine is very scoreable so I would be surprised if I was the only player here who gets hot out there. I think the winning score will be pretty low but that’s good – I think most people who come out here to watch golf want to see birdies and eagles.”
Complete first round scores:
63 N Colsaerts (Bel);
65 F Molinari (Ita); K Broberg (Swe); S Kapur (Ind);
66 F Zanotti (Par); M Foster (Eng); M Korhonen (Fin); B Virto Astudillo (Esp); L Bjerregaard (Den); B Wiesberger (Aut); S Mazzoli (am) (Ita);
67 A Perrino (Ita); J Fahrbring (Swe); C Lee (Sco); M Nixon (Eng); S Fallon (Eng); R Kakko (Fin); D Lipsky (USA); L Gagli (Ita); R Karlberg (Swe); R Wattel (Fra);
68 A Quiros (Esp); A Cañizares (Esp); M Kaymer (Ger); D Willett (Eng); P McGinley (Irl); P Lawrie (Irl); Y Yang (Kor); P Maddy (Eng); R Gonzalez (Arg); J Singh (Ind); A Hansen (Den); F Fritsch (Ger); M Lundberg (Swe); J Scrivener (Aus); P Oriol (Esp); J Lara (Esp);
69 E De La Riva (Esp); H Otto (RSA); A Pavan (Ita); R Karlsson (Swe); M Jiménez (Esp); B Hebert (Fra); D Fichardt (RSA); S Cink (USA); M Ford (Eng); S Kjeldsen (Den); J Barnes (Eng); S Chawrasia (Ind); M Tullo (Chi); E Kofstad (Nor); W Ormsby (Aus); S Hend (Aus); R Santos (Por); S Fernandez (am) (Esp); J Vecchi Fossa (am) (Ita);
70 S Hutsby (Eng); D Drysdale (Sco); M Fitzpatrick (Eng); J Morrison (Eng); D Howell (Eng); M Crespi (Ita); J Edfors (Swe); J Roos (RSA); B Evans (Eng); A Maestroni (Ita); T Fleetwood (Eng); O Fisher (Eng); D Clarke (Nir); C Paisley (Eng); P Harrington (Irl); R Dinwiddie (Eng); S Wakefield (Eng); R Jacquelin (Fra); A Levy (Fra); J Campillo (Esp); R Cabrera-Bello (Esp); M Manassero (Ita);
71 S Benson (Eng); J Lando Casanova (Fra); M Lorenzo-Vera (Fra); V Riu (Fra); E Goya (Arg); D Woltman (USA); M Bremner (RSA); R Bland (Eng); C Sordet (Fra); J Van Zyl (RSA); A Hortal (Esp); T Fisher Jnr (RSA); A Tadini (Ita); G Storm (Eng); O Farr (Wal); J Parry (Eng); C Bouniol (Fra); T Van Der Walt (RSA); D Brooks (Eng); H Joannes (Bel); L Scalise (am) (Ita);
72 D McGrane (Irl); F Aguilar (Chi); A Otaegui (Esp); C Doak (Sco); J Kim (Ita); R Rock (Eng); D Gaunt (Aus); M Fraser (Aus); J Lagergren (Swe); E Pepperell (Eng); G Mulroy (RSA); G Bourdy (Fra); T Olesen (Den); J Kruger (RSA); R Paratore (Ita); E Molinari (Ita); T Lewis (Eng); N Elvira (Esp); J Hahn (USA); R Finch (Eng); S Manley (Wal);
73 K Phelan (Irl); N Ravano (Ita); P Sjöland (Swe); B Ritthammer (Ger); R McEvoy (Eng); S Thornton (Irl); S Hansen (Den); J Walters (RSA); A Bruschi (Ita); P Uihlein (USA); O Wilson (Eng); W Homan (USA); G Moynihan (Irl); M Madsen (Den); C Del Moral (Esp); L Cianchetti (am) (Ita);
74 N Quintarelli (Ita); P Edberg (Swe); D Vancsik (Arg); G Havret (Fra); R Ramsay (Sco); M Ortolani (am) (Ita);
75 J Garcia Pinto (Esp); A Velasco (Esp); N Fasth (Swe); C Lloyd (Eng); B Neil (Sco); M Delpodio (Ita);
76 A Zemmer (Ita); M Florioli (Ita); P Widegren (Swe); L Jensen (Den);
77 F Maccario (Ita);
78 L Magini (Ita);
80 C Rocca (Ita);
81 M Grönberg (Swe).