Offaly gave it everything but in the end Galway came away from Tullamore with an impressive 5-18 to 2-15 victory.
The final scoreline may have flattered the defending All-Ireland and provincial champions but they showed all their experience to swat off a stubborn Offaly effort as goals from debutant Brian Concannon (2-1), Joseph Cooney (1-4), Conor Whelan (1-1) and substitute Jason Flynn flew past brilliant home custodian, Eoghan Cahill, who saved a Joe Canning (0-8) penalty as well as dealing well with a number of other goalbound shots.
With 8,300 looking on, that save from Canning's eleventh-minute penalty proved to be a mini turning point in the game as the outstanding Shane Dooley (1-9) netted at the other end seconds later and then pointed to make it 1-3 apiece. Concannon had hit the first Galway goal and also pointed early on, as did Whelan and Conor Cooney.
Dooley's class had the underdogs very much in touch approaching the break - and with wind advantage to come - but Cooney's goal mere seconds before the short whistle was a real dagger to the heart of Kevin Martin's side as the holders led by 2-9 to 1-7 at the interval.
Concannon's second three-pointer had the winners eight clear but Joe Bergin netted to keep the midlanders just about in contention. However, Whelan got his major on the hour and Flynn notched the fifth Galway goal in stoppage time (they hit only two goals in the entire 2017 championship!) as the Liam MacCarthy holders - who entertain Kilkenny in a fortnight - opened their round-robin account with a deserved victory over gallant opponents in the fresh midlands sunshine.
Galway - J Skehill; A Tuohy, Daithi Burke, J Hanbury; P Mannion, G McInerney, A Harte; J Coen, David Burke; J Canning (0-8, 6f, 1'65), C Mannion (0-1), J Cooney (1-4); C Whelan (1-1), C Cooney (0-2), B Concannon (2-1). Subs: J Flynn (1-0) for C Cooney, S Loftus (0-1) for J Coen, N Burke for C Mannion, R Burke for A Harte, J Glynn for J Canning.
Offaly - E Cahill (0-1f); T Spain, S Gardiner, B Conneely; D Egan, P Camon, B Murphy; D King (0-2), S Kinsella (0-1); C Mahon, D Currams (0-1), C Egan; O Kelly, J Bergin (1-1), S Dooley (1-9, 0-8f). Subs: C Kiely for C Mahon, S Ryan for B Murphy, P Murphy for C Egan, T Geraghty for D Currams, T Rigney for T Spain.
Referee - J Murphy.