净胜球数goal differential

Portugal won its match against Ghana, 2-1. that ensured that both the U.S. and Portugal finished second in Group G -- also known as the "Group of Death -- with 4 points apiece. enter the tie-breaker -- goal differential. The Americans and Portugal both scored 4 goals at the tournament after three games, but Portugal had given up 7 to the USA's 4.

葡萄牙2比1赢了加纳。这样死亡之组G组中美国和葡萄牙各积4分并列第二。现在就靠净胜球数来打破平局了。美国和葡萄牙均有4个进球，但是葡萄牙的失球数是7个，而美国的失球数仍是4个。

所谓的“净胜球数”（goal differential）就是一支球队在一轮比赛中的进球数（goals scored）减去失球数（goals allowed）。比如，美国的进球数和失球数都是4，其净胜球数就为0，而葡萄牙的进球数是4，而失球数是7，净胜球数则为-3，由此得出，美国队排在葡萄牙队之前。

如果第一轮比赛后，两队积分相同，净胜球数也相同，那么就只能靠“抽签”（draw lots）来决定哪一队出线了。