Police have lobbed teargas to disperse rowdy youth who started pelting UDA supporters with stones at the Jacaranda grounds, injuring Embakasi East UDA parliamentary candidate Francis Mureithi.
One person has also been arrested following the chaotic scenes at the venue.
Mr Mureithi was stoned by rioting youth at the grounds and had to be whisked away having suffered visible head injuries.
Deputy President William Ruto is expected to lead his Kenya Kwanza brigade for a rally at the venue amid heightened tension.
Azimio allied youth, chanting area MP Babu Owino slogans have claimed their legislator had booked the venue for a similar meeting.
Earlier, police had blocked access to the venue but later allowed entry after it emerged that the Azimio team had called off their meeting to allow the DP to continue with his rally.
Tension is however, palpable at the grounds, with police keeping opposing youth at bay.
The youth have also pelted buses that were ferrying DP Ruto's supporters to the venue.
The DP's team is expected to address the gathering from a top their vehicles as no dais has been erected.