Haseeb Hameed ended the fourth day of the first Test against India unbeaten on 62 as England began strengthening their lead over the hosts in Rajkot.
India were bowled out for 488 just before tea, with the tourists enjoying a positive start to their second innings, reaching 114 without loss and extending their lead to 163 runs.
19-year-old Hameed, making his Test debut, outshone Alastair Cook at times as he confidently secured his half century, with the captain finishing the afternoon on 46.
After a dominant display from India's Cheteshwar Pujara and Murali Vijay on day three, England finally saw their patience rewarded when Adil Rashid and Zafar Ansari took two wickets in the last two overs of the day.
India started the day on 319-4, but his late flourish on Friday gave Rashid a spring in his step on day four as he took 4-114 with the Rajkot pitch rapidly deteriorating as the day wore on. He dismissed Virat Kohli (40), Ravindra Jadeja (12) and Umesh Yadav (5), although Ravichandran Ashwin did make 70 for the hosts.
After tea, Hameed took his chance to impress on the big stage. Having notched 31 in England's first innings, he enjoyed an impressive afternoon as he sealed his first ever Test half-century from 94 balls, including a fine six off Ravi Jadeja'. Having already become only the second teenager to play for England in a Test since 1949, he is now the third youngest Englishman of all time to hit a 50 on his Test debut.
Speaking to Sky Sports, Rashid said of the teenager: "He's a quiet boy but he works very hard. He's very organised and has had a good temperament. He's tricky to bowl at, he uses his feet a lot. He works very hard in the nets and it has shown today."