Aaron Burns' strike secured Linfield a famous Europa League win against Xanthi on Thursday evening in Greece.
Blues manager David Jeffrey had admitted concerns over the heat's impact on his players in the build-up to the second qualifying round first leg.
However, the Northern Irish side faced similar energy-sapping conditions against AEL Limassol in last season's Champions League and had clearly learned from that experience.
Burns grabbed the winner in just the 25th minute, firing past Christian Gimenez after good work down the left.
Xanthi enjoyed the lion's share of possession after the goal, but Linfield held on to take a 1-0 lead into next week's second leg at Windsor Park.
There was another shock result in Scandinavia, where Frazer Wright secured St Johnstone a 1-0 victory against 22-time Norwegian champions Rosenborg.
The centre-half made the most of a brief period of Saints pressure in the opening stages to net from close range and secure his side a precious away goal.
It was quite a start to manager Tommy Wright's reign, but there were worrying moments following the 19th-minute strike and they were forced to defend stoutly to protect their lead.
Derry were another side to impress in Europe as they gave Trabzonspor a scare.
Adrian Mierzejewski and Paulo Henrique efforts gave the Turkish side a two-goal lead within 16 minutes, only for City to come storming back.