The phrase "tough matchup" means that one person or team is expected to have difficulty competing against another person or team, typically because the opponent is very strong or skilled. Full definition
This may have marked the first series between these Western conference opponents, but it became clear, fast, that it could turn into a regularly tough matchup. (sbnation.com)
This would seem to indicate that oddsmakers believe Golden State is a much tougher matchup for Cleveland than OKC. (sportsinsights.com)
Had a very tough matchup with # 1 Team Guggenheim on Thursday Night. (allsportsseries.com)