Farah qualified for the 5,000m final earlier today, finishing third in a heat that he described as "difficult".
Farah revealed that there was a lot of pushing and barging going on, but admitted that it was part and parcel of being one of the favourites.
"I am definitely tired and I think it showed out there," the 29-year-old said. "The legs didn't feel great but that is what happens. Hopefully I will recover well and look forward to the final, forget about what I have done and rest up.
"It was a really rough race. It was like being in the ring with Anthony Ogogo! As soon as they saw me there was a lot of barging and pushing. I got caught so many times.
"There is definitely a target. I am the Olympic champion over 10,000m. You just have to accept it. Hopefully the final won't be as rough because we won't have so many guys."
The men's 5,000m final takes place on Saturday evening.