Liverpool manager Brendan Rodgers accused referee Mark Halsey of playing a pivotal role in their 2-1 defeat by Manchester United at Anfield.
Rodgers was annoyed by the decision to send Jonjo Shelvey off for a lunge on Jonny Evans, and also the late penalty which was scored by Robin van Persie.
"We are bitterly disappointed but the best team lost," said Rodgers.
"We could control our players' performance but what we can't control is decisions by the referee."
Liverpool are in the bottom three and Rodgers has yet to win in his first five Premier League games in charge.
"If Jonjo gets sent off then Jonny Evans has got to be sent off as well," added Rodgers, suggesting the Manchester United defender was not blameless in attempting to win a loose ball in the 39th minute.
"If Jonjo is booked or sent off for both feet leaving the ground then Jonny Evans has got to go as well.
"It is a tackle both players have to go for but the Liverpool player then can't get sent off and the Manchester United player stays on the field."
Steven Gerrard gave Liverpool the lead just after the break, but Rafael Da Silva quickly equalised before Van Persie's decisive 81st minute penalty gave United their first win in six attempts at Anfield.
Rodgers was equally angry about Halsey's decision to award the spot-kick, saying: "Everyone who saw it will say it is never a penalty.
"Glen Johnson has made a fantastic recovery run and I don't know why Antonio Valencia goes down to be honest.
"Then at the other end Luis Suarez gets a toe on the ball to take it away from the defender, there is contact, but then there is no penalty given."
Rodgers' problems increased with fears that defender Agger could face a lengthy absence with medial knee ligament damage.
Striker Fabio Borini was taken off at half-time with a swollen ankle and Martin Kelly limped off late on as Liverpool finished the game with only nine men.