Ronald Koeman is unsure whether Southampton deserved to concede two penalties in their 2-1 Premier League loss to Sunderland, but blasted his side's display at the Stadium of Light.
Jose Fonte's foul on Danny Graham enabled Jordi Gomez to give Sunderland the lead from the spot in the 21st minute.
And, after Sadio Mane had levelled for Southampton, Gomez restored the hosts' advantage from 12 yards after James Ward-Prowse had been sent off for bringing down Jermain Defoe.
The defeat leaves the south-coast club four points adrift of fifth-placed Liverpool and gives Tottenham the chance to put the same gap between the London club and Southampton when they face Manchester City on Sunday.
Koeman said in quotes reported by BBC Sport: "I don't know if the penalties are good decisions by the referee. I will have to watch the clips.
"The thing that has frustrated me the most is the performance of my own team because we did not play at our level.
"The 10 minutes after half-time were our worst of the season so far.
"We only showed our level with one less player on the pitch. We played much better football and were the better team when it was 10 men against 11. That is so strange it is unbelievable."
