I guess in the end Ma Chao did not heed Han Sui warning and joined hands with 8th instead. I thought the whole thing with Zhang Fei helping Ma Chao is to make sure Ma Chao doesnt join hands with the 8th though. Then again its been foreshadowed that five pecks of rice is actually 8th handiworks so it makes sense they would meet.
Another interesting aspect is that 8th went against 6th and Zhao Yun back then and now Zhao Yun alone would fight 8th and Ma Chao.