Ronaldo was one of the major players to move during the transfer window, sealing a switch from Juventus back to Old Trafford, where he starred from 2003 to 2009.
The 36-year-old Portuguese forward scored a double for his country during the national team break, making the all-time leading scorer in international football, fueling the hype about his possible second debut.
“He has been having a good pre-season with Juventus, he has played for the national team,” Solskjaer said during his pre-match news conference.
“He has had a good week with us here and he will definitely be on the pitch at some point that is for sure.”
Ronaldo was released early by Portugal from national duty, after copping a yellow card leading to a one-game suspension for his shirt-less celebration following his second goal against the Republic of Ireland.
The Portuguese’s early arrival at Old Trafford has helped him integrate and eased his workload in the lead-up to the Magpies clash.
United are likely to be without Fred due to Brazil invoking a five-day rule on players who did not participate in their recent World Cup qualifiers.
“Kevin trained well last week, part alone, part with the other players who were here plus the Under-18s,” City boss Pep Guardiola said.
Arsenal will be desperate for their first points of the season at home to struggling Norwich City.
The Gunners are likely to be boosted by the return to availability of defensive duo Ben White and Gabriel Magalhaes while Granit Xhaka is suspended.