United's squad were jogging a warm-up lap on Tuesday at their Hindmarsh base when lightning hit, damaging signage at the stadium.

Players ran to seek shelter with star winger Craig Goodwin admitting the lightning strike rattled the group.

"Lightning struck right above us ... it was a little bit frightening, to be honest," Goodwin said.

"But we're all good, everyone just ran inside.

"It was probably the closest any one of us has been to a lightning strike, so it was pretty loud; literally right above us."

Adelaide's players returned to the ground when the lightning storm passed, training through heavy rain as they continue preparing for Friday night's A-League semi-final against Perth Glory.

"For most of us it was a recovery session ... we got out of it what we wanted and the weather conditions haven't affected us too much," Goodwin said.

The Reds will meet competition favourites Perth with just four days rest after their taxing win over Melbourne City on Sunday, when Ben Halloran scored the winner with just 90 seconds remaining in extra-time.

The Glory will have had an 11-day break come game day after earning the first weekend of finals off by finishing top and claiming the Premiers' Plate.

Goodwin said Adelaide players couldn't afford to dwell on their brief break or their gruelling elimination final.

"The thing we have got to focus on is not using the 120 minutes (against City) as any type of excuse for this game," he said.

"It's a short turnaround, we know that.

"But we have the time, we're fit enough from this season and pre-season to go out against Perth on Friday and play as we always do.

"We are very confident.

"Obviously we know that Perth finished top this year and they have got a great side and a great coach, and it's going to be a tough game.

"They're going to be the favourites but on our day we can beat anyone."