Bulldogs scare Broncos.
The Super League outfit had to overcome horrendous playing conditions at a sodden Mount Pleasant in addition to enthusiastic opponents and in the end were good value for a 22-16 fifth-round victory.
"We knew it was going to be tough," said Powell. "In front of that sort of crowd and against a John Kear-coached team who have got some very good and enthusiastic players, we had to dig in.
"I thought the boys were pretty impressive today with some of the individual performances and the way they went about their business.
"Some of those young London blokes have only ever played at nice grounds - they've never played proper rugby league on a hill with the rain coming across sideways before - so it was a bit of an experience for them.
"They'll get some good experience out of that. Some of our Aussie guys won't have played in those conditions either."
Playing up the marked slope and into the driving wind and rain, the Londoners made a perfect start when tries from Matt Cook, Antonio Kaufusi and Jamie O'Callaghan put them into a 16-0 lead.
However, the Bulldogs rallied magnificently to cut the gap to four points by half-time thanks to converted tries from Danny Maun and Mark Applegarth, and the Broncos were forced to defend stoutly in the second half to secure their first away win for almost 12 months.
"However ugly, it was important for us to get the win, regardless of how it was achieved," added Powell, whose side are next to bottom of Super League with only two wins from 12 games.
"We have struggled away from home so to get that win is a big thing and, now we're in the quarter-finals, we can look forward.
"It would be nice to get a home tie - we've performed very well at home all year - but, if we have to come away, hopefully we can show the same character we showed."
Batley coach John Kear, who has masterminded Cup final wins with Sheffield Eagles and Hull, got the conditions he hoped for and was also delighted with his side's performance.
"I'm very proud of my part-time lads," he said. "I thought it was a manful effort.
"We wanted levelling conditions and we certainly got them. The players are absolutely frozen. You've got to compliment both sets of players because they were horrific conditions."
Trailing only 16-12 with the slope in their favour, the game was set up for an upset and Kear admitted his side failed to fully utilise the conditions in the second half.
"As the conditions worsened, the field got heavier and opportunities became less and less," he said.
"I was disappointed with our second-half kicking game but I think that was in part due to London's defence."