From Naruto manga volume 400
So, it was a mistake all long this time for Sasuke to kill his own blood brother, Uchiha Itachi. The truth has unveiled by the Uchiha Madara, that Itachi's mission from Kohona was to destroy the whole uchiha clan. Being double agent is really hard when he loves peace so much, but when considering the best option, ending the record book of his own clan was the only choice he could chose. Poor Sasuke. He is going to regret for hating his own brother so much after he was told the truth by Madara.
However, it's been a question on who actually won in the battle between the brothers? Well, the battle started on with two in genjutsu world, then they fought with ninjutsu in real world. It was unquestionable that Itachi did have problem in defeating Sasuke when his health condition had deteriorate due to excessive use of his Mangekyo Sharingan before. However, after reading volume 400, I am pretty sure that Itachi had no intention of taking his own brother's eyes. Maybe he was planning to plant his eyes to Sasuke during the battle, but Sasuke was too good for him at the moment and defensed it.
Nevertheless, after a hard and intense defence by Sasuke, Itachi still managed to control the battle with his Amaterasu and the final jutsu.
Therefore, from my abstract thought, Itachi won the battle against Sasuke but just right before he died, he planted all my eye techniques to Sasuke and fall in order to protect Sasuke from Madara. If Itachi has the intention to kill Sasuke from the beginning, then he surely has the opportunity to do just right before he fall. Sasuke was out of chakra and can't fend off Itachi's final jutsu. It's so obvious that Sasuke going to lose at the time.
From:
Naruto Forum: Goodbye Itachi