This randomized study will compare maintenance therapy with Avastin (bevacizumab) + Xeloda (capecitabine) versus Avastin alone, in patients with HER2-negative metastatic breast cancer who have not progressed during first-line therapy with docetaxel + Avastin. Eligible patients will receive up to 6 x 3 week cycles of treatment with Avastin (15 mg/mg IV on Day 1 of each cycle) + docetaxel (75-100 mg/m2 IV on Day 1 of each cycle). Those patients who do not progress will be randomized to 3 week cycles of either a) Avastin (15 mg/kg IV on Day 1 of each cycle) + Xeloda (1000 mg/m2 po bid on Days 1-14 of each cycle) or b) Avastin alone. Study treatment will continue until disease progression, unacceptable toxicity, patient request for withdrawal or end of study, and the target sample size is 100-500 individuals.