An elf named Glorfindel killed a Balrog in the First Age. Balrogs are Maiar that were corrupted by Morgoth. We know they can be killed by powerful beings, like the wizards, in single combat because Gandalf killed one.
Sauron was also one of the Maiar. Or more precisely, he was one of the lesser Ainur who entered the world, and the lesser Ainur were called Maiar.
Only a very powerful elf could even hold a fight against a Maia. When the Fellowship encountered a balrog in the mines of Moria, Gandalf said "this foe is beyond any of you". He didn't say, "well, except maybe Legolas". So clearly he didn't think Legolas was powerful enough to kill a balrog, but maybe Elrond or Galadriel could.
A human defeated Sauron during the siege against the Mount Doom in the Last Alliance, but I see that as stupidity and luck. Sauron made a stupid move of trying to grab Isildur with his ring-hand and Isildur getting lucky when he used the hilt-shard of the sword to slice that hand. I doubt Isildur or any human could defeat Sauron in open combat.
I'm not asking if an elf could have cut the ring from Sauron's finger as Isildur did, or if an elf could have tossed the ring into Mount Doom. I am asking about open combat the way Gandalf fought the balrog in open combat.
So if an Elf slew a Balrog in single combat, which is a Maia, could an elf also slay Sauron in single combat?
Please provide quotes and links from canon sources for your answers.