The Vikings have waived QB John David Booty, league sources told NFL Network’s Jason La Canfora.

Introduced by the customary Viking horn, Brett Favre took the field at 6:20 p.m. local time, with fellow Minnesota QBs Tarvaris Jackson and John David Booty. Sage Rosenfels won’t play in tonight’s preseason game against the Chiefs because of an ankle injury.

New Vikings QB Brett Favre will start tonight’s preseason game against the Chiefs and play one to two series, according to a team official.

The Vikings now have four quarterbacks on their roster, and NFL execs I spoke to told me they anticipate Tarvaris Jackson being shopped in the near future now that Brett Favre is in town.

Do not panic America, Brett Favre, took the practice field at the Vikings’ Winter Park practice facility wearing his familiar No. 4 jersey. The former No. 4 — backup QB John David Booty — has switched to No. 9.

Check the Vikings practice facility in the near future to see if Booty is driving a new car.

Vikings QB Tarvaris Jackson went through the majority of practice and saw his most extensive action since spraining his left knee Saturday morning.

Vikings coach Brad Childress said Tarvaris Jackson stayed inside Sunday to receive treatment on his sprained left knee, which is expected to sideline the quarterback until sometime next week. Childress also said the team doesn’t plan to sign another QB.