The phrase "a popular opponent" is correct and usable in written English.
It can be used to describe someone who is well-liked or respected, particularly in a competitive context, such as sports or politics.
Example: "In the upcoming election, the incumbent faces a popular opponent who has garnered significant support from the community."
Alternatives: "a well-liked rival" or "a favored challenger".
Candidates tend not to want to appear to be a sore loser to a popular opponent.
Asked in the newspaper interview published Sunday how he planned to overcome such a popular opponent, Mr. Steinbrück pointed out that he was pretty popular himself.
Relatives of Dr. Hugo Spadafora, a popular opponent whose decapitated body was found in 1985, recently demanded that Mr. Noriega disclose the location of Dr. Spadafora's skull.
This makes clubs more money (but do they need it? Not if they're more economical) by adjusting tickets daily to reflect factors such as a popular opponent or the opposing teams' major stars.
Harris is a "very polarizing figure," he said, running against a popular opponent who appeals to independent voters.
If the Magic are playing a popular opponent and the crowd is big, the member will end up in the cheap seats.
At ringside, not long after the final bell, Mayweather, Sr., took a moment to revel in his son's victory over a more popular opponent.
The Twins are a weaker, less popular opponent than, say, the Boston Red Sox.
-- Maryland will hold its primaries today to choose a Democratic opponent for popular Republican Gov. Larry Hogan.
Mr. Karzai's most popular opponent last year, former Foreign Minister Abdullah Abdullah, warned in an interview that without more substantial reform "the election in September will be a setback for democracy" and could create "another political stalemate, if not a crisis".
The governor then went on to win re-election to a second term last November by a slightly smaller margin, despite running against a well-funded, popular Democratic opponent.
