Google plans to unveil an NFC mobile payment service tomorrow that will be available on phones from US operator Sprint Nextel, reports Bloomberg. The service will let consumers with specially equipped phones that run on Google’s Android operating system pay for goods and redeem coupons with their handsets. The technology is already available on the Android-powered Nexus S from Sprint. The report follows a Wall Street Journal report in March that Google was partnering with MasterCard and Citigroup to allow the financial giants’ customers to use their debit and credit cards to pay for purchase from their Android smartphones. Google’s mobile-payment service would face competition from alternatives such as ISIS, a joint effort of AT&T, Verizon Wireless and T-Mobile USA. ISIS plans to roll out its service in two cities, including Salt Lake City, in early 2012.