1.c4 Nf6 2.Nc3 e6 3.e4 d5 4.cxd5 exd5 5.e5 Here 5...d4, 5...Ne4 and 5...Nfd7 are most often played. This is a quite different line, where the two sides clash early in the centre. Since White does not have to play 3.e4, he could avoid this line.