The Small Device on Gill's Forehead at Eden Park, Explained

India captain Shubman Gill caught everyone's eye during the first ODI against New Zealand at Eden Park in Auckland, with a small device worn on the side of his forehead.

He had already been seen wearing it in training after arriving in New Zealand, and he kept it on during the match.

The device is called Temple, a health and fitness wearable from a team associated with Zomato co-founder Deepinder Goyal.

It sticks to the skin near the temple and uses light sensors, in a system called BrainFlow, to track changes in blood flow to the brain, along with a strain reading called Entropy.

Badminton star PV Sindhu has also been seen wearing Temple during international competitions.

Gill has not publicly explained why he wears it, and there is no confirmation that it is part of India's official fitness programme.

The sighting also raised questions about the rules for wearables during a match.

Devices that can send or receive messages are barred from the players' area, while a monitor that only collects readings may be treated differently under the regulations, depending on the rules and any approval needed.