Leeds started the game pressing very heavily every time Chelsea touched the ball, but as the first half wore on, cracks typically began to appear. Leeds predictably got tired, and Michael Brown decided to slow the game down by repeatedly doing his best impression of Sergio Busquets (minus any footballing talent of course).
Leeds began to sit back and defend, satisfied with simply trying to hit Chelsea on the counter when they pushed numbers forward. They'd take advantage when David Luiz was caught forward in attack, taking a 1-0 lead when they charged forward with numbers.
Chelsea looked to have leveled through Victor Moses, but the goal was correctly called back when Fernando Torres was caught offside during the buildup to the goal. I hate to keep harping on Torres for his fundamental mistakes, but there is absolutely no excuses for being caught offside in that situation. It remained 1-0 Leeds, and we'll have work to do in the second half because of that.
On a side note, it's always amusing when BeIN televises an English game. The commentators never seem overly familiar with the majority of the players that have played in England for long stretches of time, but they seem to love guys like Marko Marin, Eden Hazard, and Cesar Azpilicueta that they've seen far more often with their continental coverage. It's so opposite the overly Premier League biased commentary we get with most domestic games that it takes me a few minutes to get used to it.