Eliyahu HaNavi, drink up !

I was asked by a very chashuve student why we only wake up and mention Eliyahu Hanavi at the end of the seder when we pour 'his' cup.
I saw two answers that I wanted to share with you.
Eliyahu's cup is a misnomer, points out Rav Shlomo Zalman Auerbach, Zatzal, ( as quoted in the Roshei Yeshiva Haggadda ) because the cup is not for him at all. We know that the four cups are drunk, in part, to correspond to the four statements of redemption ( Leshonos HaGeula ). They are : VeHotzeiti, VeHitzalti, VeGaalti, VeLakachti ( In various pesukim, Hashem says "And I will ... Free, Save, Redeem and Take you out of Egyption bondage ). The gemara in Pesachim maintains that there is a fifth pasuk that is perhaps also a statement of redemption : 'VeHeveiti' - and I will Bring you to the Land of Israel. In order to resolve this conflict we pour the fifth cup ( in case it is a lashon geulah ) but, we don't drink it ( in case it is not a lashon geulah ).
Like many cases in the gemara - we state that we await Eliyahu Hanavi to come and resolve the difficulty - that's why it became known as Eliyahu's Cup.