1-2遭逆转，切尔西上一次欧冠半场领先后输球是在2013年（1-2被逆转：切尔西上次欧冠半场领先仍输球要追溯到2013年）

Clarifying Chelsea's match

The user sent a message about Chelsea's recent performance, mentioning that they lost 1-2 after leading at halftime, with the last similar instance being in 2013. It feels like they want details about that 2013 match, but they didn't ask directly. Should I confirm and clarify? The match I’m thinking about is Chelsea vs. Basel in the 2013-14 Champions League group stage. In this match, Chelsea led 1-0 at halftime before losing. So, I’ll confirm this context for the user!Confirming Chelsea's match details

The user’s message about a "1-2" loss aligns with Chelsea leading at halftime and then losing. That specific match was against Basel on September 18, 2013, during the group stage, where Chelsea led 1-0 through Oscar but ended up losing 2-1 due to goals from Salah and Streller. I’ll keep my answer concise and factual, and since they asked for details from 2013, I won't overload with extra match info unless necessary. I’m ready to provide the specifics in Chinese!Providing Chelsea match details

Here’s the information you requested:

• Opponent: Basel
• Competition: UEFA Champions League Group Stage
• Date: September 18, 2013, at Stamford Bridge
• Halftime: Oscar scored at 45', leading 1-0
• Second half: Goals by Salah at 71' and Streller at 81' resulted in a 1-2 loss

This was the most recent time Chelsea led at halftime in the Champions League and then lost. I’ll keep it concise and straightforward!