Everton boss Dave Moyes praised his defence after their 2-0 victory over West Ham.
Yakubu extended his scoring run to five from three games but Moyes' credit went to his defenders.
West Ham manager Alan Curbishley was left to bemoan a lengthening injury list after his side suffered their second defeat to Everton in three days.
Yakubu had pounced on a late mistake on Wednesday night to book Everton a place in the Carling Cup semi-final.
Danny Gabbidon and Luis Boa Morte were both missing while Carlton Cole was forced off at half-time with a long-standing hip problem.
"I can't ask any more from the players," said Curbishley.
"I am getting the best out of them but we need that bit of quality at both ends of the pitch."