Marshmello and Bastille's Happier is battling for Number 1 on this week's Official Singles Chart

Plus Lady Gaga is in line to score her first UK Top 10 single in five years.

Marshmello and Bastille are challenging Calvin Harris and Sam Smith for the Number 1 spot on this week's Official Singles Chart. 

The mysterious US producer, real name Christopher Comstock, climbs two places to Number 2 with his latest single Happier ft. Bastille on this week's Official Chart Update. Watch the music video - released last week - below.

The pair are chasing Calvin & Sam's Promises, currently on track for a fifth week at the summit. 

New entries and high climbers 

Mark Ronson and Diplo aka Silk City charge three places to Number 4 with Electricity ft. Dua Lipa, Rita Ora jumps six spots to Number 8 with Let You Love Me, and George Ezra's Shotgun rebounds seven runs to Number 9 following his performance on Strictly Come Dancing. 

Meanwhile, this week's highest entry looks set to come from Lady Gaga and Bradley Cooper's Shallow. The song, which features in the pair's new film A Star Is Born, opens at Number 10 and could mark Gaga's first UK Top 10 single in five years.

Big climbers this week include singer-songwriter Freya Ridings' Lost Without You, so far up nine to Number 11, and Sigala's Just Got Paid ft. Ella Eyre, Meghan Trainor and French Montana vaults 20 spots to 13 following the release of the producer's debut album Brighter Days. Read our new interview with Sigala, where he talks about Avicii and working with Kylie Minogue, here.

Lil Wayne looks set to land three new entries on the singles chart from the release of his new album Tha Carter V: Mona Lisa ft. Kendrick Lamar (20), Don't Cry ft. XXXTentacion (21) and Let It Fly ft. Travis Scott (27). 

Finally, three more songs could be making their Top 40 debut this Friday: DJ Snake's Taki Taki ft. Selena Gomez, Cardi B and Ozuna (33), Olly Murs' brand new single Moves ft. Snoop Dogg (39) and MK's Back & Forth ft. Jonas Blue and Becky Hill (40). 

View the Top 100 Official Singles Chart Update in full