The Senators have gone 5-5-1 since Phaneuf arrived and are seven points out of the second wild card into the Stanley Cup Playoffs from the Eastern Conference.
Senators wing Zack Smith tried to put the best spin on how Phaneuf's return to Toronto might go.
"It doesn't happen a lot, traded to a rival, but I'm sure he can expect a warm welcome," he said. "He was their captain for a lot of years, did a lot of good things for them. You never know. It's hard to predict fans, especially in Toronto."
When it was suggested there was little chance the Maple Leafs fans would cheer Phaneuf, he said: "I'm being optimistic here. You never know. For sure, there are some hardened fans out there."
Phaneuf, 30, immediately improved the Senators depth on defense with his arrival. He has formed a solid second pair with Cody Ceci, 22.
"He makes our whole team better," coach Dave Cameron said.
Speaking specifically about Phaneuf's impact on Ceci, Cameron said: "Well, he's an NHL 800-game player, so he's poised and vocal. Calmness. Sometimes when things are getting scattered you just need a calm voice to settle everybody down and he has that."