Hull will return home from their New South Wales tour empty handed after going down 24-18 to St George Illawarra in Sydney.
The Black and Whites produced a valiant effort, with Albert Kelly scoring two first-half tries to give them an interval lead, and they were level at 18-18 until Kurt Mann went over for the all-important try with five minutes left.
Beaten 24-10 by Wigan a week earlier in the first Super League match to be staged outside Europe, Hull produced a fitting response in an entertaining clash at ANZ Stadium.
They were without skipper Danny Houghton, vice-captain Scott Taylor
and experienced second rower Mark Minichiello, but Kelly showed his class and there were also impressive contributions from winger Bureta Faraimo and prop Liam Watts.
St George had England prop James Graham and Australia half-back Ben Hunt making their first appearances, along with former Hull KR and Wakefield forward Mitch Allgood, but it was England international Gareth Widdop who proved the difference.
Hull were full of invention from the start, with full-back Jamie Shaul splitting the Dragons defence with a scything run and second rower Sika Manu reaching the line only to lose the ball in Widdop's last-gasp tackle.
It was no surprise when the visitors took the lead, Kelly releasing Jake Connor and regathering the centre's neat kick to touch down for his first try.
St George struck back with two tries in 13 minutes through centre Tim Lafai and winger Jason Nightingale but Widdop was only able to add one conversion and Hull turned around in front thanks to the skill of Kelly.
It was a chance created from nothing as the former Gold Coast Titans half-back took Marc Sneyd's pass from dummy half and smashed a hole in the Dragons' defence to grab his second try.
Sneyd's second conversion made it 12-10 but Hull had a let-off three minutes before half-time when prop Jeremy Latimore had a try disallowed by the video referee for a knock-on.
The Australian side made the better start to the second half and Widdop was instrumental in slick backline moves that produced two tries in five minutes for Papua New Guinea winger Nene Macdonald.
The tries were scored too far out for Widdop to improve and a six-point lead was wiped out after 55 minutes when Watts powered his way over for Hull's third try, with Sneyd kicking his third goal.
A draw might have been a fair result but Hull were under the cosh in the last 10 minutes and their defence finally cracked to allow Mann a way through and Jai Field added the conversion.