Originally Posted by KennyBSAT

Yes. Push a payment from any account that allows you to pay a Citi Mastercard, do a billpay at a store that accepts Mastercard payments, pay with cash or check in a Citi branch, pay with a debit card or check over the phone, snail mail a check...

Use absolutely any method by which one could pay a credit card other than using your card account to pull a payment.