Last year, Lambert took his squad to Germany for a trio of games against lower league opposition.
"I've never experienced anything like it yet those boys have not only coped, they have beaten sides 20-odd games into their season, who deal with these extreme conditions all the time.
"It was another win against Houston and it rounds off this mini-tour really well.
"Dallas was warm but in Houston it's a dead heat. It was really tough. But I was really happy with the team.
"I was delighted with them. It's been great. It really has. It's been a tough few days. But the lads have been excellent.
"Dallas was a great venue as was Houston. They have made us welcome. Everything on this trip has been very good.
"In fact it's been the best pre-season in my time here."
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