Konstantinos Mitroglou kept Benfica on track for an unprecedented fourth consecutive Portuguese league title with the winning goal in a 1-0 victory at Moreirense.
The Greece striker headed in Pizzi's free-kick three minutes before half-time.
The victory restored the defending champion's one-point lead over Porto, who had moved to the top after beating Belenenses 3-0 the previous day thanks to goals from Danilo Pereira, Tiquinho Soares and Yacine Brahimi.