The 25-year-old full-back will undergo a scan on Thursday after pulling up during the second half of Boro's 1-0 Championship defeat at Cardiff on Saturday.
Friend said: "I have never had a hamstring problem, but it's hopefully not too bad."
The defeat in South Wales was Boro's first in 10 games in all competitions and left them sitting in third place in the table.
However, with home clashes against Bristol City and Huddersfield to come inside four days, Friend is confident they will bounce back.
He said: "We have got two home games now and recently we've been very good at home. Hopefully we can get another two wins there."