Newcastle were beaten 2-1 by Tottenham Hotspur at St. James’ Park in their Premier League opener.
However, the Magpies’ performance was rather encouraging, with both Rondon and Muto being introduced as late substitutes.
The pair both made an impact, with Rondon even hit the bar late on, as Newcastle searched for an equaliser.
And Benitez was pleased by what he saw from his new recruits this summer.
He said: “They did well. They were trying hard, now it is just about improving the understanding with the rest of their team-mates. So they know what we want to do and how the other team-mates will react.
“Once they get that, they will be better, but with Muto, Rondon, Joselu and Ayoze (Perez), we have four different kinds of strikers, and that can be good.”
Newcastle didn’t do all the business that they wanted in the summer, with Benitez still wanting another number 10.
However, Muto and Rondon should improve Newcastle’s attacking options, for the upcoming season.
Newcastle's next match comes on Saturday, when they take on Cardiff City, and Rondon may well be selected to start.