keep one’s feet on the ground 復習

YEKATERINBURG, Russia--Japan will look to further explore their attacking potential when they face Senegal in a battle of the surprise contenders to advance to the knockout stage from Group H on Sunday.

中略

"We must keep our feet on the ground .... we have to take into account that we played against 10 men for almost 90 minutes," skipper Makoto Hasebe said, referring to Carlos Sanchez's dismissal which gave Japan the advantage against Colombia.
"The next game will be a different story, we have to think about that," the defensive midfielder added.

http://www.asahi.com/sp/ajw/articles/AJ201806230022.html

今回取り上げるのはkeep [have, get] one’s feet on the groundです。『ジーニアス英和辞典』を引いたところ「足が地についている，実際的である」とありました。『オックスフォード現代英英辞典』を参照すると“to have a sensible and realistic attitude to life”と定義されています。なので上記では「落ち着いて」といった訳が合うと思いました。(Kiwi girl)