Sportal.co.nz 27.Jun.2013Getty Images
Beale, who spent two weeks in rehab last month, played the final 41 minutes of the 23-21 loss after replacing injured full-back Berrick Barnes late in the first half.
The 24-year-old had a major impact on the match but his return will be remembered for the pair of potentially match-winning penalties he missed in the final five minutes of the series opener.
Mowen leapt to his team-mate's defence on Wednesday and predicted the former John Eales medallist is primed for a big performance in Saturday's must-win second Test in Melbourne.
"He was disappointed (after the game) but I think Kurtley is a very strong bloke and I think people probably don't give him enough credit for how mentally strong he is," Mowen, who made an impressive Test debut last Saturday, said.
"The guys came around him very quickly and said 'mate, not to worry'.
"The fact of the matter is we had the chance to win with that kick because he kicked one earlier ... he's bounced right back and he's been a big performer for us in the last couple of days at training."
Beale was suspended in March for punching Rebels skipper Gareth Delve and team-mate Cooper Vuna on the team bus.
He returned in early May against the Chiefs but violated an agreement with the Rebels not to drink alcohol after going out with team-mates after the match and was suspended for a second time.
The former schoolboy prodigy subsequently made the decision to check himself into rehab.
Mowen, a team-mate of Beale's at the Waratahs for four seasons, says he has noticed a big change in Beale's demeanour after reuniting in Wallabies camp in recent weeks.
"I've known Kurtley for about four or five years and I think over the last six or seven months he's really changed as a bloke, he's really taken a big step forward and matured a lot and the way he played on the weekend was a good reflection of that," Mowen said.
"As a squad we're extremely proud of what KB's done, he's had to make a lot of hard decisions over the past couple of months and own those decisions very publicly.
"But the way he's come back from those situations has been amazing ... and you can't come on the field and perform the way he did for us unless you're mind is in the right position and your body's right.
Meanwhile, Mowen questioned the Lions' ability to cover the loss of injured lock and lineout General Paul O'Connell who will miss the rest of the series with a broken arm.
"I think potentially that could be a big challenge for them," Mowen said.
"Obviously they've got good cover and I believe they'll probably go with (Geoff) Parling in that role.
"But I think when you look at the side he had out on the field he's obviously a huge General for them and he's got massive respect from both side in the game so when you lose a player of that type of calibre it does take a massive effort to cover for him."
Mowen added skipper James Horwill's availability for the Wallabies after he was cleared of stamping Alun Wyn Jones is a 'massive' boost for the home side.