The resolve shown by the Wallabies since the summer and the form of the likes of Will Genia, Michael Hooper and Liam Gill will make Warren Gatland and co even more aware of the difficulty of what lies according to the former Bath and England man.
"This Lions series looks harder to win by the week," Barnes wrote in his Sky Sports column.
"It seems a long time since New Zealand was heaping humiliation upon the Wallabies in the Rugby Championship and the Aussie press was calling for the head of Robbie Deans.
"Since Australia ended New Zealand's winning run with a draw in Australia things have improved at a worrying rate for Lions fans.
"The hammering in Paris apart last autumn, Australia beat both Wales and England, the two leading Six Nations sides and the form of their leading players in Super Rugby is a cause for concern - for the Lions."
Scrum-half Genia has been sensational since returning from knee surgery last month, while Hooper has continued to show he is more than capable of stepping into David Pocock's considerable shoes once again this summer.
Gill is pushing Hooper hard for that No7 shirt as well and, when you consider that veteran George Smith seems back to his best and on the verge of extending his short-term loan deal from Suntory Sungoliath, the Wallabies look well blessed in the back row.
And with both the Brumbies and Reds currently challenging hard for top honours with more points at this stage of the season than any of their New Zealand or South African rivals, Barnes reckons the Aussies have plenty of reasons to be optimistic ahead of the opening Test in Brisbane on June 22.
"Admittedly, the Waratahs, Rebels and Force are all in the lower echelons of the league but the Reds are finding some fine form and the Brumbies have shown consistency enough to lead the competition. The bulk of the Wallabies are sharp," added Barnes.
"The Reds are on a roll and steering them with accuracy and invention is Will Genia. He has returned from his injury a better player than ever. On his current form he is one of the most influential players on the planet.
"Even when Australia lose a genuine world-class player they are able to produce a whole warren of rabbits as is the case with the openside situation. David Pocock is up there with the leading sevens on the planet and is a loss but the standard of open side play from Australians in Super Rugby is quite staggering.
"Michael Hooper is starring in a struggling Waratahs team. I nominated him as Man of the Match when Australia beat England at Twickenham, he was outstanding then and continues to improve. And he has to because Liam Gill is putting the heat on him in no uncertain terms.
"The Reds flanker is a contender for the player of the tournament to date but ironically he would probably be eclipsed by the current form of one George Smith. Words cannot describe the completeness of his performance for the Brumbies against the Highlanders last Friday. At the turnover, terrorising the opposing fly-half, linking forwards and backs or making try-scoring breaks, he did it all."
One area that Barnes admits the Wallabies might be missing a trick, however, is in the selection, or more accurately non-selection of Quade Cooper and Kurtley Beale.
The pair missed out on the recent logistical camp in Sydney and, while Deans hasn't shut the door on their summer hopes, they face a real battle to get back into the mix before the Suncorp Stadium encounter with the Lions.
Barnes isn't convinced that the duo will win the series for the hosts if eventually chosen but he does feel their inclusion would add excitement to an already mouth-watering match up.
"Genia has reinvigorated his mate at fly-half, Quade Cooper. The headline hogging fly-half has been in the news for being omitted from Deans' first Australian squad of 30 but there is time for the manager to change his mind should the maverick play as he did against the Chiefs.
"Cooper divides opinion but, love or loathe him, it is hard to dispute his originality in a game that has become perhaps too mechanical over the years. The series will be all the more exciting for his presence.
"His friend, James O' Connor, wants the 10 shirt, as does the bad boy, Kurtley Beale.
"What I would love, purely from an excitement point of view, would be Cooper at 10, O' Connor at 14 and Beale at 15. Warren Gatland might also fancy that back line of stellar talented erratic - or he may find the very thought frightening."