United thought that they had done enough for the win when Robin van Persie gave them a first-half lead, but Clint Dempsey struck in injury time to earn the hosts a share of the spoils.
"Before the game we would have taken a point," Ferdinand told BBC Sport. "We defended well as a team. You have to do that as you have to stand up and be counted and we did that today until the last 30 seconds.
"They are a team who are improving under a new manager, so we leave here not too down."
The draw has seen United's lead at the top of the table cut down to five points.