Normally, when an imperfectly mode-locked 532nm ps laser is incident upon a Cu:KNSBN photorefractive crystal, no self-pumped phase conjugation can occur. We report however, for the first time to our knowledge, that if a photorefractive waveguide is first created in the crystal by a mode-locked beam of the same wavelength, then self-pumped phase conjugation can be induced for the imperfectly mode-locked beam.