Willy Caballero made his Premier League debut for Manchester City at the weekend, leading to enquiries into the future of regular City number one Joe Hart.
When questioned whether Hart will play on Tuesday, the Chilean responded: "Yes, he's in a very good moment also.
"It's a crucial game because Roma won their first match and we lost," he said.
"It will be a very tough group and we cannot drop points here at home. It's very important for us to win that game."
Following the decision to drop Hart for the game at the KC Stadium, which has since been confirmed by Pellegrini as merely squad rotation, there had been talk in the papers that Liverpool would attempt to swoop in and sign up the England international as top class competition for Simon Mignolet.
Such a move was always likely to be a little farfetched, despite Hart's seemingly disappointed attitude on the bench during the 4-2 win, but Manchester City fans panicking at the thought of losing one of their longest serving players can rest a little easier after Pellegrini's comments on the 27-year-old.
Hart has made over 250 appearances for the Citizens since making his debut in 2007, and his approaching his 50th cap for England. It was also rumoured the former Shrewsbury man was considered for the Three Lions captaincy before Roy Hodgson plumped for Wayne Rooney.
Pellegrini appears keen to keep Hart on his toes, after dropping the stopper for a period of last season's title winning campaign in favour of Romanian rival Costel Pantilimon, a player that has since departed for Sunderland.
If Hart was to under perform against Roma, or in any other high profile game, it isn't beyond the realms of possibility that the former Villarreal manager will be inclined to bring in Caballero, a player he worked with before at Malaga.
And if that happens, Hart may not be prepared to spend another prolonged spell on the bench.