Farah was made to work hard in his heat of the 5,000m this morning, eventually finishing third in 13 minutes 26 seconds to reach Saturday's final.
"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 10,000 metres. You just have to accept it. Hopefully the final won't be as rough because we won't have so many guys."
Farah is the first British man to win Olympic gold in the 10,000m, while he will be aiming to follow in the footsteps of Ethiopia's Kenenisa Bekele (2008) by claiming the long-distance double.
He insisted he had not thought about withdrawing from the 5,000m despite the draining effects of last Saturday, when he won Britain's third gold in the space of 45 minutes.
"By the time I got back it was a late night and there was a lot of emotion," he said. "It is something I had never done before and now I
know how much it takes out of you.
"[Now] there is zero pressure. I am not putting any pressure on myself. I want to do well for the crowd because the support drives you further. Whatever I do I will give 100%. I am full of confidence and having the home crowd will definitely drive me more."
Team-mate Nick McCormick actually ran quicker than Farah in the considerably faster second heat, but could only finish 12th in 13:25.70 to miss out on a place in the final as a faster loser.
"I've got something to be proud of, I'll have no regrets in 20, 30 years when I'm sitting there," McCormick, 30, said. "I was finishing strong, I just learned on that penultimate lap you've got to stay in contact.
"It's a fantastic atmosphere, it was over too quickly and it's not often you say that about a 5k. I am just so proud of myself to be here. I've got to go away now and reflect and see where it went wrong and push on from here to Moscow (for the World Championships) next year.
I really think I can make the final in Moscow."
Elsewhere, Sophie Hitchon improved her own British record in the last round of qualifying to reach the women's hammer final.
Hitchon was set to bow out after a first-round attempt of 67.21m and a foul in the second, but the 21-year-old then produced a superb throw of 71.98m, 37cm further than her previous best and enough for 10th
overall after an anxious wait for the second qualifying group to finish.
"I was just proud to be on the team and to come here at a morning
session, with a full crowd and throw a PB and a British record, it was amazing," Hitchon said.
"I did the same at Europeans (leaving it to the last throw) and I
don't know why. I like to put a lot of pressure on myself for some reason. I knew it was there, I've been throwing really well in training.
I was ready and obviously it showed."
Steve Lewis had an easier time in qualifying for the pole vault final, a single clearance of 5.50m proving enough to go through as one of the 14 qualifiers, meaning the 26-year-old can try to emulate his room-mate Greg Rutherford, the long jump champion, in Friday's final.
"It's been a tough week for me watching my room-mate Greg Rutherford come out and win a gold medal," Lewis said. "I have just been
sitting in my room. It was great getting up this morning, up at 6 and got the job done.
"Greg has been an inspiration to me, being around and training with him. It has been an awesome lead-up to the Olympics. That kind of energy around the village and around the apartment is amazing. There is a great vibe in Team GB right now.
"I think I can jump 5.80-5.90 and that will be in the mix for a medal. I don't know what it will take to win but I will give it my best shot."
Britain's Lynsey Sharp also made it to the semi-finals of the women's 800m in impressive fashion, the Scot under pressure to justify her place after her selection for the 800m with only the 'B' qualifying time meant four athletes with the 'A' standard - Jenny Meadows, Emma Jackson, Jemma Simpson and Marilyn Okoro - missed out.
The European silver medallist finished second in her heat behind defending Olympic champion Pamela Jelimo, easily qualifying automatically for the semi-finals.
"Obviously it (the selection controversy) was in the back of my mind, but I just thought of it as any other race," Sharp said. "I've run
in races of a higher quality than that this year so that's prepared me well."
Asked if she had received any messages from the women who had missed out, the 21-year-old added: "No, I mean like we are not friends. We never have been, but Marilyn's on the team (in the 4x400m) relay so obviously I've spoken to her.
"She's a really nice girl, I don't think she would ever say anything bad. I haven't heard from the other girls, but I don't really care, it's not my problem."
There was disappointing news for Daniel Awde in the decathlon, the 24-year-old being forced out with a knee injury after the second event, the long jump.
Awde had set a personal best of 10.71s in the 100m to lie seventh
overall, but then committed two fouls in the long jump and already looked to be struggling before managing 6.83m with his final attempt.
"I've had a flare up of patella tendinitis and if I continued it would probably rupture," Awde said. "It's been a real rollercoaster ride. We try to find solutions to it. It works for about a week, find another solution and that works for about a week.
"If you spoke to me at the start of the year I wouldn't have expected to be here in the first place, it's been a real bane of my life
for the last two years.
"I'm in the best shape of my life. I was so ready for this to put
on a good show, entertain the crowd. I was ready but my knee wasn't. Without being too arrogant, if the pain is enough to make me stop and pull out of my home Olympics, then it's too painful."
PA
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