But the tourists coped admirably in the 26-degree heat to claim a 10-6 win over the Eagles at Toyota Park and put down an early marker for the season ahead.
Darbyshire insisted: "I wasn't surprised by the fitness the players showed. Theyâ00ve worked hard in the past 12 weeks of pre-season and reaped the benefits of that hard work on Sunday. The first game is always the toughest one, add to that the conditions â00 the heat and humidity - and the fact that weâ00re on the road as well doesn't make it any easier.
â00I was very pleased the way the guys applied themselves in very trying conditions. It was a good test of their character and they came through. You can train as hard as you want in pre-season but the games bring your fitness to another level.â0
The Wigan native, who is most known for his near 17-year association with English rugby league club Warrington Wolves, was appointed by Munster in June and having settled in quickly, knows his new team face a bigger challenge when Alan Gaffney's Saracens visit Cork on Friday week.
"Our next pre-season game against Saracens will be tougher still in terms of the quality of the opposition weâ00re facing. The Americans are mostly amateur - all with day jobs - while next time weâ00ll be facing a fully professional outfit and we can expect another tough game," Darbyshire added.
"But bottom line is we travelled a long way (to America), came away with a win and as I already said, the players reaped the benefits for their hard work."
Meanwhile, Munster Rugby have changed the kick-off times for their two pre-season friendlies at Musgrave Park - the September 7 clash with Saracens and the meeting with Italian side Viadana on September 14 will now both start at the earlier time of 6.30pm.
The changes are to avoid clashing with those night's televised Rugby World Cup matches (France v Argentina on September 7 and England v South Africa on September 14).