【Analysis】It is easy to get the total number of matches in the group stage as the number of groups $\times$ (number of groups -1$) \div 2$, which can give the total points of 4 teams, and then we can discuss whether a team can advance with 6 points or 7 points.

【Solution】Solution: 4 teams play a single round-robin tournament, which involves a total of $4 \times 3 \div 2=6$ matches. After each match, the total points of the two teams are either 2 points (a draw) or 3 points (a win and a loss). Therefore, the total points of all teams after 6 matches do not exceed 18 points.
(1) If a team scores 7 points, the total points of the remaining 3 teams do not exceed 11 points. It is impossible for two teams to have a total score greater than or equal to 7 points, so this team must advance.
(2) If a team scores 6 points, it is possible that two other teams also score 6 points, and their goal difference is better than this team, so this team may still not advance.

In summary, for the school team to secure a top-two finish in this friendly tournament, they need to score at least 7 points. Therefore, the answer is 7.
10. (10 points) On September 21, 2015, the Ministry of Education announced the list of national youth campus football characteristic schools. Xiao Xiao's school was on the list. To better prepare for the elementary school football league to be held in the city next year, the school's team will recently play a football friendly match with three other teams. The matches will be played in a round-robin format (i.e., each team will play one match against every other team). The rules are: 3 points for a win, 0 points for a loss, and 1 point for each team in a draw. The ranking will be determined by the total points, and if two teams have the same points, the goal difference, head-to-head results, and other factors will be considered to determine the ranking. To ensure that Xiao Xiao's school team finishes in the top two in this friendly match, they need to score at least $\qquad$ points.