Johanna Konta was knocked out of the Porsche Grand Prix in Stuttgart by Anastasija Sevastova as her struggles on clay continued. The British No1 is inexperienced on the surface at the highest level and it showed in a scrappy 6-3, 7-5 defeat by Sevastova, who also won their meeting at the US Open last year.

Konta began the second-round match with a break of Sevastova’s serve in the first game but lost the next three and did not hold her own serve until the fourth attempt. The Latvian, ranked 19 places below Konta at No26, produced three aces in a row on her way to clinch the opening set and recovered from 3-1 down in the second to level. A missed forehand opportunity then cost Konta as she was broken in the 11th game and Sevastova served out the straight-sets victory with her sixth ace.

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The result meant there would be no immediate rematch between Konta and Romania’s Simona Halep. The pair met last Sunday in the fiery Fed Cup tie between Romania and Great Britain in Constanta, with Halep winning 6-1, 6-3.

The worldNo5 said she had been given extra motivation by the previous day’s events, when Konta had left the court in tears during her clash with Sorana Cirstea after saying she felt threatened by abuse from the crowd in Halep’s home city.

Maria Sharapova recorded the second victory of her comeback to reach the quarter-finals. After a nervy start and ultimately comfortable win against Roberta Vinci in the first round, Sharapova stepped up a level to beat a fellow Russian, Ekaterina Makarova, 7-5, 6-1.

Speaking in an on-court interview shown on BT Sport, the 30-year-old Russian said: “Being the second match and playing yesterday and getting all the emotions out, I feel I settled down a little bit and I was able to focus on my game. I executed a great plan. Practice is so different. You can prepare the best you can and when go out you just have to trust it. It was definitely great to come out and play matches and being in the quarter-finals here again is quite special.”

The five-times grand slam champion generated huge power off her groundstrokes from the off and wore down the dogged Makarova over an hour and 19 minutes. The draw has been kind to Sharapova, who is returning from a 15-month dope ban, and she will face another unseeded player in the quarter-finals in Estonia’s Anett Kontaveit.

The world No72 is in great form, having reached the final of her last tournament in Switzerland before upsetting French Open champion Garbiñe Muguruza in the second round.

Sharapova’s two victories have already ensured she will be back in the top 400 in the rankings on Monday, edging her closer to earning direct entry for Wimbledon.

She has two more tournaments, in Madrid and Rome, in which to secure enough points, while reaching the final in Stuttgart would earn her entry into French Open qualifying without the need for a wildcard.In Barcelona, Andy Murray was given a good workout against Feliciano López as the world No1 booked a quarter-final place with a 6-4, 6-4 victory. The Spaniard provided stubborn resistance before Murray progressed into the last eight where he will meet Albert Ramos-Viñolas, who defeated him in three sets at Monte Carlo last week and Roberto Bautista-Agut on Thursday 6-2, 3-6, 6-4.