USA: Pittsburgh - Singles - Main
1/16-finals Hernandez A. Callahan H. 2:0 (6:2, 6:2) details 27.06.2018
USA: Waco - Singles - Main
1/8-finals Callahan H. Shane R. 0:2 (63 :7, 2:6) details 29.11.2017
1/16-finals Butler S. Callahan H. 0:2 (4:6, 4:6) details 28.11.2017
USA: Columbus - Singles - Main
1/8-finals Callahan H. Sarkissian A. 0:2 (2:6, 5:7) details 23.11.2017
1/16-finals Vaghela V. Callahan H. 0:2 (4:6, 3:6) details 21.11.2017
USA: Laguna Niguel - Singles - Main
Quarter-finals Callahan H. Craig H. 1:2 (3:6, 6:1, 3:6) details 22.09.2017
1/8-finals Callahan H. Bullard J. 0:0 RET. (4:0) details 21.09.2017
1/16-finals Descotte M. F. Callahan H. 0:2 (3:6, 4:6) details 19.09.2017
USA: Claremont - Singles - Main
1/16-finals Verboven L. Callahan H. 2:1 (7:68 , 4:6, 6:4) details 13.09.2017
USA: Edwardsville - Singles - Main
Semi-finals Ram Harel O. Callahan H. 2:1 (6:3, 1:6, 6:3) details 12.08.2017
Quarter-finals Perez A. Callahan H. 1:2 (6:3, 1:6, 4:6) details 11.08.2017
1/8-finals Callahan H. Rybakov A. 2:0 (7:5, 7:5) details 10.08.2017
1/16-finals Callahan H. Johnson E. J. 2:0 (6:4, 6:2) details 08.08.2017
USA: Decatur - Singles - Main
1/8-finals Dougaz A. Callahan H. 2:0 (6:4, 6:4) details 03.08.2017
1/16-finals Nguyen D. Callahan H. 1:2 (6:4, 1:6, 64 :7) details 02.08.2017
USA: Champaign 2 - Singles - Main
1/16-finals Riffice S. Callahan H. 2:0 (7:5, 6:3) details 24.07.2017
USA: Champaign - Singles - Main
1/16-finals Adams H. Callahan H. 2:1 (6:3, 5:7, 6:3) details 18.07.2017
USA: Pittsburgh - Singles - Main
1/8-finals Callahan H. Lama G. 1:2 (6:4, 63 :7, 4:6) details 29.06.2017
1/16-finals Kirchheimer S. Callahan H. 0:2 (3:6, 1:6) details 28.06.2017
USA: Rochester - Singles - Main
1/16-finals Lama G. Callahan H. 2:1 (6:4, 0:6, 7:65 ) details 20.06.2017
USA: Buffalo - Singles - Main
1/8-finals Callahan H. Uchida K. 0:2 (3:6, 4:6) details 15.06.2017
1/16-finals Callahan H. Gozun A. 2:0 (6:1, 7:64 ) details 14.06.2017
USA: Orlando 2 - Singles - Main
1/16-finals Ramanathan R. Callahan H. 2:0 (6:1, 6:2) details 01.03.2017
USA: Indian Harbour Beach - Singles - Main
1/16-finals Kypson P. Callahan H. 2:1 (3:6, 6:4, 6:2) details 23.02.2017
USA: Weston - Singles - Main
1/16-finals Callahan H. Vasilyev I. 1:2 (2:6, 6:0, 4:6) details 25.01.2017
USA: Columbus 2 - Singles - Main
1/16-finals Krueger M. Callahan H. 2:0 (6:4, 6:3) details 22.11.2016
United Kingdom: Barnstaple - Singles - Main
Quarter-finals Callahan H. Nielsen F. 1:2 (6:4, 1:6, 2:6) details 11.11.2016
1/8-finals Gabb R. Callahan H. 1:2 (6:2, 1:6, 4:6) details 10.11.2016
1/16-finals Bauvy R. Callahan H. 0:2 (4:6, 4:6) details 09.11.2016
United Kingdom: Sheffield - Singles - Main
1/8-finals Patael B. Callahan H. 2:0 (6:3, 6:4) details 02.11.2016
1/16-finals Ridout R. Callahan H. 0:2 (4:6, 1:6) details 01.11.2016
United Kingdom: Loughborough - Singles - Main
1/16-finals Callahan H. Marti Y. 0:2 (4:6, 2:6) details 26.10.2016
USA: Fountain Valley - Singles - Main
1/8-finals Garanganga T. Callahan H. 2:1 (6:2, 1:6, 6:4) details 29.09.2016
1/16-finals Callahan H. Ejupovic E. 2:0 (7:5, 6:1) details 27.09.2016
USA: Irvine - Singles - Main
1/16-finals Callahan H. Gomez L. 0:2 (3:6, 65 :7) details 21.09.2016
USA: Claremont - Singles - Main
1/16-finals Callahan H. Trombetta T. D. 0:2 (2:6, 4:6) details 13.09.2016
USA: Champaign - Singles - Main
1/16-finals Polmans M. Callahan H. 2:0 (6:3, 6:3) details 09.08.2016
USA: Decatur - Singles - Main
1/16-finals King E. Callahan H. 2:0 (6:3, 7:5) details 03.08.2016
USA: Pittsburgh - Singles - Main
1/16-finals Callahan H. Kwiatkowski T. S. 0:2 (4:6, 1:6) details 28.06.2016
USA: Rochester - Singles - Main
1/8-finals Pasha N. Callahan H. 2:0 (6:3, 7:65 ) details 23.06.2016
1/16-finals Carter A. Callahan H. 0:2 (2:6, 1:6) details 22.06.2016
USA: Buffalo - Singles - Main
1/8-finals Gosea F. Callahan H. 2:0 (7:64 , 7:5) details 16.06.2016
1/16-finals Callahan H. Garza D. 2:0 (7:5, 6:4) details 14.06.2016
Italy: Frascati - Singles - Main
1/16-finals Callahan H. Carli C. 1:2 (4:6, 6:3, 5:7) details 18.05.2016
USA: Plantation 2 - Singles - Main
1/16-finals Callahan H. Ore J. A. 1:2 (6:3, 4:6, 5:7) details 17.02.2016
USA: Weston - Singles - Main
1/16-finals Spencer W. Callahan H. 2:0 (6:0, 6:3) details 29.01.2016
USA: Champaign - Singles - Main
1/16-finals Ramanathan R. Callahan H. 2:1 (4:6, 6:2, 6:1) details 12.08.2015
USA: Pittsburgh - Singles - Main
1/8-finals Gomez E. Callahan H. 2:0 (6:2, 6:3) details 02.07.2015