Australian fly-half James O'Connor finished a jinking run with a try in the very last play of the first half, to narrow the scoreline to 19-10.
The Lions lead at the break thanks to Alex Corbisiero's early try, and 14 points from the boot of Leigh Halfpenny.
Australia could have been ahead, but turned down five opportunities to kick penalties for goal in the first period.
More top news
This week Carl talks to psychologist Amy McClelland about new research on the sleeping habits of babies.
For those who have mobility problems the idea of a walk in the Welsh mountains may seem unlikely. But this new scheme may change that.
Any rain will eventually clear this afternoon, bringing brighter weather behind it.