"I hope Luna always commentates from now on... Loser's Lurgy..."
-- Ron to Harry, later in the Hospital Wing (HBP19)
Luna Lovegood provides the commentary for the fourth Quidditch match of the season. Although playing as Gryffindor’s Keeper, Cormac McLaggen grabs a Beater’s bat and cracks Harry’s skull, knocking him unconscious. While Harry is taken to the Hospital Wing, Hufflepuff win the match by 320 points to 60 (HBP19).
On Ron's birthday (1 March), McLaggen states that the match is in one week. This would put the match on 8 March.
The essay "An Almanac of Quidditch at Hogwarts" points out that this:
"appears to be the first Gryffindor game in seven seasons involving only one Weasley, unless Bill played on the Gryffindor team alongside Charlie."