In the 57th minute, with the score at 2-0 to the Baggies, Lambert brought on Gabby Agbonlahor, Andreas Weimann and Fabian Delph to replace Libor Kozak, Aleksandar Tonev and Yacouba Sylla in a bid to change the game.
The three players had been battling injuries prior to the fixture and Lambert felt they gave a good account of themselves in helping Villa force a 2-2 draw with second-half goals from Karim El Ahmadi and Ashley Westwood.
"We spoke about it and we thought we had to get them on pretty quickly, but we were actually going to wait a bit longer," he told Sky Sports.
"But we thought we needed to get a goal and the three of them made a huge contribution. They have been big players those three and to lose them at the time we did was a bit of blow.
"Full credit to the three of them. They only started to train on Friday, they came on and I thought they were outstanding."
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