ISLAMABAD, November 21: An embattled Prime Minister Nawaz Sharif today got a new jolt when the Pakistan Supreme Court admitted a petition challenging a constitutional amendment brought in by his government, which stripped the President of his powers to dismiss a government.However, Sharif got some relief as the court postponed the contempt case, in which he appeared in person twice this week, till November 28.A three-member Bench, headed by Chief Justice Sajjad Ali Shah, admitted a petition by Karachi-based advocate Syed Iqbal Haider, seeking to restore President Farooq Ahmed Leghari's powers to dismiss the federal government, and set the next hearing for November 27.Another five-member Bench, also headed by Shah, postponed hearings in the contempt case till next Friday after all the respondents, including Sharif's counsel, requested for time to submit replies to the chargesheet.The petition by Haider, who also leads the Sindh-based Muslim Welfare Movement, said the 13th amendment, brought in by the Sharif government soon after it came to power in February this year, was ultra vires of the constitution and opened the door for martial law in the country.The amendment scrapped Leghari's powers to sack the government and national assembly.