back and forth. For instance, in the 2004–05 UEFA Champions League round of 16 between Barcelona and Chelsea, Barcelona were ahead on aggregate after a 2–1 win in the first leg at home. During the second leg held in London, Chelsea first scored three straight goals to take the lead on aggregate (4–2), but Barcelona responded with two goals to level the aggregate score at 4–4 while taking the lead on away goals (2–1). Chelsea scored again, though, to advance on aggregate, 5–4. In the 2018–19 UEFA Champions League semi-finals between Tottenham Hotspur and Ajax, Ajax led the tie from the 15th minute of the first leg (in a 1–0 away victory in London) until the 95th minute of the second leg (at that point still up 3–2 on aggregate), when Tottenham's Lucas Moura completed a hat-trick in Amsterdam that leveled the aggregate score at 3–3 while eliminating Ajax, 3–1, on away goals. Usage The away goals rule is applied in many football competitions that involve two-leg fixtures, including the knockout stages of the CAF Champions League, CAF Confederation Cup and any two-legged playoffs in qualification for the FIFA World Cup or European Championships. From 2014 until 2018, Major League Soccer in the U.S. and Canada used the away goals rule in the MLS Cup Playoffs, in which the conference semi-finals and finals (the quarterfinals and semi-finals of the overall tournament) were two-legged. The rule was first applied in this competition when the Seattle Sounders defeated FC Dallas in the 2014 Western Conference semi-finals. In the 2019 MLS season, two-legged ties were eliminated in favour of a single-elimination knockout format throughout the entire playoffs. In the Liga MX, the away goals rule always applied to the playoff games until the 2020–21 season. This was also applied to the final games until the 1995–96 season where Necaxa beat Celaya F.C. In those games, Necaxa was able to pull a 1–1 tie in the game in Celaya, then the team was able to hold a 0–0 tie in Azteca Stadium to win the championship. After that final, the away goals rule was removed from the final game and in case of a tie after the two games, it will go to extra time and a penalty shootout if needed, as happened in the Invierno 1999 season where Atlas F.C. and Deportivo Toluca where tied 5–5 at the end of the second game