 Complete the following phrase:  At the beginning of the season, Bonaventura switched his number from 28 to 5. He started Milans opening match of the Serie A season against Torino. In the second half of the match, he was fouled inside the six-yard box by Joel Obi and Milan was given a penalty which was converted by Carlos Bacca to complete his hat-trick in Milans 32 win. He scored his first goal of the season on 2 October in Milans memorable comeback against Sassuolo as the game finished 43. The following week he assisted MBaye Niangs goal against ChievoVerona in a 31 win. He also assisted Susos first goal in the 22 draw against city rivals, Inter. On 23 December 2016, Bonaventura scored the equalising goal in the Supercoppa Italiana against Juventus; he later netted his penalty in the resulting shoot-out, helping Milan to a 43 victory. He signed a contract extension through 2020 with Milan on 18 January 2017. On 29 January, Bonaventura suffered an injury in a match against Udinese which ruled him out for the rest of the season following surgery on a thigh injury; earlier in that match, he scored Milans goal in the 21 loss. He returned to the squad for the last game of the season against Cagliari on 28 May, but couldnt make an appearance during the match as Milan lost 21. He ended the season with 5 goals and 4 assists in 22 appearances in all competition as Milan finished 6th in Serie A, was knocked out of Coppa Italia in quarter-finals by eventual champions Juventus, and also won the 