The decision was revealed at the morning skate in Ottawa.
The rookie Hammond helped Ottawa rally to an improbable playoff berth with his impressive play over the final weeks of the regular season, but he and the Senators lost their opening two playoff games in Montreal.
Anderson was Ottawa's starter for much of the season before he and then-backup Robin Lehner were injured, paving the way for Hammond's ascension.
Hammond, 27, made his first NHL start on Feb. 18 and promptly won 14 out of 15, with the lone loss coming in a shootout. He matched a 76-year-old record by allowing two or fewer goals in his first 12 NHL starts and finished the regular season with a 20-1-2 record and a sparkling 1.79 goals-against average as Ottawa stormed from out of contention to qualify for the playoffs on the regular season's final day.
Along the way, Hammond became a cult hero of sorts, with a nickname ("the Hamburglar") to match.
But Hammond didn't look as sharp in the first two games of the Senators' playoff series against Montreal, losing 4-3 in Game 1 and 3-2 in overtime in Game 2, putting Ottawa in a hole as the series shifts back home on Sunday.
Ottawa defence lets down Hammond
The Canadiens know they'll have to adjust for the change in venue.
"My message to my teammates is they're going to have their best game of the year in their building the next time we play them," Montreal defenceman P.K. Subban told the NHL's official website. "So we need to be prepared for that, we need to be ready. They could have easily taken at least one win out of these two."
The Canadiens tallied four second-period goals on Hammond in their 4-3 victory in Game 1, then scored twice in the same period Friday before winning 3-2 in overtime.
It was the first time Hammond had suffered consecutive defeats in the NHL, although Ottawa's defensive play did him few favours. Hammond faced 39 shots on Wednesday and 42 on Friday — the second-most he's seen all season — and Montreal's Alex Galchenyuk capitalized on a Senators' turnover to score the game-winner.
"That's why you play the game," coach Dave Cameron said. "You can watch it on video and draw it up and do all you want. Stuff happens. We fanned on it ... Obviously I would have liked a save there, but you can't turn it over."
Anderson, 33, lost the starting job to Hammond after injuring his hand in late January, then posted a 3.42 GAA in his final four starts after returning to the net last month. However, he did stifle the Canadiens with a 1.80 GAA in Ottawa's 4-1 series win in the 2013 post-season.
In the opposite net, Montreal's Carey Price is seeking his 20th career post-season win.
Subban, Pacioretty return in style
Subban's slash on Ottawa's Mark Stone in Game 1 earned him a five-minute major and game misconduct, but he avoided a suspension and took advantage Friday. The former Norris Trophy winner blasted a slapshot past Hammond for Montreal's second goal of the game and led the team with 29:06 of ice time.
"I didn't play the whole first game and I wanted to be better," Subban said. "I had to be ... I think of myself as a player who steps up in big games and makes a difference. I always felt that the more pressure people put on me, the better I'll play. I wanted to be better tonight for my teammates."
Max Pacioretty proved equally necessary in his return. He missed the season's final two contests and Game 1 due to a head injury, but he returned in Game 2 to score his sixth career post-season goal.
Stone played through a microfracture in his wrist — suffered as a result of Subban's slash — and tallied two assists.
"[Stone's] a character guy for us," winger Clarke MacArthur said. "For him to step in there as a young guy, it's gritty of him. Hats off to him."