Both have been named to be extremely powerful kunoichi, Tsunade being named the most powerful kunoichi and Konan was the only person for the whole of shippuden (besides Naruto) to have fought Tobi to seriousness and she would have killed him had it not been for the sharingan's OP abilities.
Amegakure (site of Pain vs Jiraiya)
Tsunade has full Creation Rebirth, Katsuyu is ready to be Summoned, 4th War Tsunade
Konan has Dance of the Shikigami, Paper Person of God Technique is prepared, before fight with Tobi.
If the Paper person of god jutsu is prepared then tsunade is basically done for, when tsunade gets caught with that technique tsunade will obviously release her seal, but would that save her from from SIX HUNDRED BILLION PAPER BOMBS!!, even though she survives from that blast she will drown eventually. Tsunade can't fly, nor fast,which makes her an easy target for konan. Even before konan launches that technique will tsunade's punches even do anything? ,-, konan can separate herself into papers...plus tsunade has no technique that can deal with konan's papers, like jiraiya and his oil release.