Sasuke blushes when Sakura talks about how Sasuke is her dream when introducing herself to Team 7, and also after Sakura hugged him during Kakashi's bell test.
I admit for a while I was skeptical of this. I thought some of my fellow SasuSaku fans were getting over-excited and that Sasuke's blushing was more likely due to the art style (sometimes characters in Part I are drawn with blush marks in the manga during Part I, even when they are not really blushing or have no real reason to blush). What made me reconsider my original dismissal of Sasuke blushing was that in in the war arc, the introduction scene is redrawn in a flashback in the newer "Shippuden" style and Sasuke is still drawn as blushing. That made me think that the blush marks were intentional, and Sasuke is indeed actually blushing (though the anime version removed that detail). Additionally, the color version of the manga also clearly shows Sasuke blushing. Sakura is the only girl to cause Sasuke to blush.