Frank told a press conference on Friday: "Two top players. Sonny has been here for 10 years and finally got his well deserved trophy in the summer. Cristian Romero, World Cup winner, Copa America winner twice, very important for us. Both have trained well and set the standards. Both will play tomorrow [against Reading] and I'm very happy."
Son was named club captain by previous head coach Ange Postecoglou, with Romero one of three vice captains alongside James Maddison and Guglielmo Vicario. But Frank has claimed he will have the final say over the captaincy for the new campaign even if the incumbent leaders retain the armband in pre-season.
"I haven't decided on [who the captain is] yet," he added. "I have a long list of bullet points to get through. [Son] was captain last season and tomorrow we'll have two 45 minutes and Son and Romero will be the captains in both. I haven't decided on the captain yet."